static int exif_process_IFD_TAG(image_info_type *ImageInfo, char *dir_entry, char *offset_base, size_t IFDlength, size_t displacement, int section_index, int ReadNextIFD, tag_table_type tag_table)
{
	size_t length;
	unsigned int tag, format, components;
	char *value_ptr, tagname[64], cbuf[32], *outside=NULL;
	size_t byte_count, offset_val, fpos, fgot;
	int64_t byte_count_signed;
	xp_field_type *tmp_xp;
#ifdef EXIF_DEBUG
	char *dump_data;
	int dump_free;
#endif /* EXIF_DEBUG */

	/* Protect against corrupt headers */
	if (ImageInfo->ifd_nesting_level > MAX_IFD_NESTING_LEVEL) {
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "corrupt EXIF header: maximum directory nesting level reached");
		return FALSE;
	}
	ImageInfo->ifd_nesting_level++;

	tag = php_ifd_get16u(dir_entry, ImageInfo->motorola_intel);
	format = php_ifd_get16u(dir_entry+2, ImageInfo->motorola_intel);
	components = php_ifd_get32u(dir_entry+4, ImageInfo->motorola_intel);

	if (!format || format > NUM_FORMATS) {
		/* (-1) catches illegal zero case as unsigned underflows to positive large. */
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Process tag(x%04X=%s): Illegal format code 0x%04X, suppose BYTE", tag, exif_get_tagname(tag, tagname, -12, tag_table), format);
		format = TAG_FMT_BYTE;
		/*return TRUE;*/
	}

	if (components <= 0) {
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Process tag(x%04X=%s): Illegal components(%d)", tag, exif_get_tagname(tag, tagname, -12, tag_table), components);
		return FALSE;
	}

	byte_count_signed = (int64_t)components * php_tiff_bytes_per_format[format];

	if (byte_count_signed < 0 || (byte_count_signed > INT32_MAX)) {
		exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Process tag(x%04X=%s): Illegal byte_count", tag, exif_get_tagname(tag, tagname, -12, tag_table));
		return FALSE;
	}

	byte_count = (size_t)byte_count_signed;

	if (byte_count > 4) {
		offset_val = php_ifd_get32u(dir_entry+8, ImageInfo->motorola_intel);
		/* If its bigger than 4 bytes, the dir entry contains an offset. */
		value_ptr = offset_base+offset_val;
        /*
            dir_entry is ImageInfo->file.list[sn].data+2+i*12
            offset_base is ImageInfo->file.list[sn].data-dir_offset
            dir_entry - offset_base is dir_offset+2+i*12
        */
		if (byte_count > IFDlength || offset_val > IFDlength-byte_count || value_ptr < dir_entry || offset_val < (size_t)(dir_entry-offset_base) || dir_entry <= offset_base) {
			/* It is important to check for IMAGE_FILETYPE_TIFF
			 * JPEG does not use absolute pointers instead its pointers are
			 * relative to the start of the TIFF header in APP1 section. */
			if (byte_count > ImageInfo->FileSize || offset_val>ImageInfo->FileSize-byte_count || (ImageInfo->FileType!=IMAGE_FILETYPE_TIFF_II && ImageInfo->FileType!=IMAGE_FILETYPE_TIFF_MM && ImageInfo->FileType!=IMAGE_FILETYPE_JPEG)) {
				if (value_ptr < dir_entry) {
					/* we can read this if offset_val > 0 */
					/* some files have their values in other parts of the file */
					exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Process tag(x%04X=%s): Illegal pointer offset(x%04X < x%04X)", tag, exif_get_tagname(tag, tagname, -12, tag_table), offset_val, dir_entry);
				} else {
					/* this is for sure not allowed */
					/* exception are IFD pointers */
					exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Process tag(x%04X=%s): Illegal pointer offset(x%04X + x%04X = x%04X > x%04X)", tag, exif_get_tagname(tag, tagname, -12, tag_table), offset_val, byte_count, offset_val+byte_count, IFDlength);
				}
				return FALSE;
			}
			if (byte_count>sizeof(cbuf)) {
				/* mark as outside range and get buffer */
				value_ptr = safe_emalloc(byte_count, 1, 0);
				outside = value_ptr;
			} else {
				/* In most cases we only access a small range so
				 * it is faster to use a static buffer there
				 * BUT it offers also the possibility to have
				 * pointers read without the need to free them
				 * explicitley before returning. */
				memset(&cbuf, 0, sizeof(cbuf));
				value_ptr = cbuf;
			}

			fpos = php_stream_tell(ImageInfo->infile);
			php_stream_seek(ImageInfo->infile, displacement+offset_val, SEEK_SET);
			fgot = php_stream_tell(ImageInfo->infile);
			if (fgot!=displacement+offset_val) {
				EFREE_IF(outside);
				exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_WARNING, "Wrong file pointer: 0x%08X != 0x%08X", fgot, displacement+offset_val);
				return FALSE;
			}
			fgot = php_stream_read(ImageInfo->infile, value_ptr, byte_count);
			php_stream_seek(ImageInfo->infile, fpos, SEEK_SET);
			if (fgot<byte_count) {
				EFREE_IF(outside);
				EXIF_ERRLOG_FILEEOF(ImageInfo)
				return FALSE;
			}
		}
	} else {
		/* 4 bytes or less and value is in the dir entry itself */
		value_ptr = dir_entry+8;
		offset_val= value_ptr-offset_base;
	}

	ImageInfo->sections_found |= FOUND_ANY_TAG;
#ifdef EXIF_DEBUG
	dump_data = exif_dump_data(&dump_free, format, components, length, ImageInfo->motorola_intel, value_ptr);
	exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Process tag(x%04X=%s,@x%04X + x%04X(=%d)): %s%s %s", tag, exif_get_tagname(tag, tagname, -12, tag_table), offset_val+displacement, byte_count, byte_count, (components>1)&&format!=TAG_FMT_UNDEFINED&&format!=TAG_FMT_STRING?"ARRAY OF ":"", exif_get_tagformat(format), dump_data);
	if (dump_free) {
		efree(dump_data);
	}
#endif

	if (section_index==SECTION_THUMBNAIL) {
		if (!ImageInfo->Thumbnail.data) {
			switch(tag) {
				case TAG_IMAGEWIDTH:
				case TAG_COMP_IMAGE_WIDTH:
					ImageInfo->Thumbnail.width = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
					break;

				case TAG_IMAGEHEIGHT:
				case TAG_COMP_IMAGE_HEIGHT:
					ImageInfo->Thumbnail.height = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
					break;

				case TAG_STRIP_OFFSETS:
				case TAG_JPEG_INTERCHANGE_FORMAT:
					/* accept both formats */
					ImageInfo->Thumbnail.offset = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
					break;

				case TAG_STRIP_BYTE_COUNTS:
					if (ImageInfo->FileType == IMAGE_FILETYPE_TIFF_II || ImageInfo->FileType == IMAGE_FILETYPE_TIFF_MM) {
						ImageInfo->Thumbnail.filetype = ImageInfo->FileType;
					} else {
						/* motorola is easier to read */
						ImageInfo->Thumbnail.filetype = IMAGE_FILETYPE_TIFF_MM;
					}
					ImageInfo->Thumbnail.size = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
					break;

				case TAG_JPEG_INTERCHANGE_FORMAT_LEN:
					if (ImageInfo->Thumbnail.filetype == IMAGE_FILETYPE_UNKNOWN) {
						ImageInfo->Thumbnail.filetype = IMAGE_FILETYPE_JPEG;
						ImageInfo->Thumbnail.size = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
					}
					break;
			}
		}
	} else {
		if (section_index==SECTION_IFD0 || section_index==SECTION_EXIF)
		switch(tag) {
			case TAG_COPYRIGHT:
				/* check for "<photographer> NUL <editor> NUL" */
				if (byte_count>1 && (length=php_strnlen(value_ptr, byte_count)) > 0) {
					if (length<byte_count-1) {
						/* When there are any characters after the first NUL */
						ImageInfo->CopyrightPhotographer  = estrdup(value_ptr);
						ImageInfo->CopyrightEditor        = estrndup(value_ptr+length+1, byte_count-length-1);
						spprintf(&ImageInfo->Copyright, 0, "%s, %s", ImageInfo->CopyrightPhotographer, ImageInfo->CopyrightEditor);
						/* format = TAG_FMT_UNDEFINED; this musn't be ASCII         */
						/* but we are not supposed to change this                   */
						/* keep in mind that image_info does not store editor value */
					} else {
						ImageInfo->Copyright = estrndup(value_ptr, byte_count);
					}
				}
				break;

			case TAG_USERCOMMENT:
				EFREE_IF(ImageInfo->UserComment);
				ImageInfo->UserComment = NULL;
				EFREE_IF(ImageInfo->UserCommentEncoding);
				ImageInfo->UserCommentEncoding = NULL;
				ImageInfo->UserCommentLength = exif_process_user_comment(ImageInfo, &(ImageInfo->UserComment), &(ImageInfo->UserCommentEncoding), value_ptr, byte_count);
				break;

			case TAG_XP_TITLE:
			case TAG_XP_COMMENTS:
			case TAG_XP_AUTHOR:
			case TAG_XP_KEYWORDS:
			case TAG_XP_SUBJECT:
				tmp_xp = (xp_field_type*)safe_erealloc(ImageInfo->xp_fields.list, (ImageInfo->xp_fields.count+1), sizeof(xp_field_type), 0);
				ImageInfo->sections_found |= FOUND_WINXP;
				ImageInfo->xp_fields.list = tmp_xp;
				ImageInfo->xp_fields.count++;
				exif_process_unicode(ImageInfo, &(ImageInfo->xp_fields.list[ImageInfo->xp_fields.count-1]), tag, value_ptr, byte_count);
				break;

			case TAG_FNUMBER:
				/* Simplest way of expressing aperture, so I trust it the most.
				   (overwrite previously computed value if there is one) */
				ImageInfo->ApertureFNumber = (float)exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel);
				break;

			case TAG_APERTURE:
			case TAG_MAX_APERTURE:
				/* More relevant info always comes earlier, so only use this field if we don't
				   have appropriate aperture information yet. */
				if (ImageInfo->ApertureFNumber == 0) {
					ImageInfo->ApertureFNumber
						= (float)exp(exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel)*log(2)*0.5);
				}
				break;

			case TAG_SHUTTERSPEED:
				/* More complicated way of expressing exposure time, so only use
				   this value if we don't already have it from somewhere else.
				   SHUTTERSPEED comes after EXPOSURE TIME
				  */
				if (ImageInfo->ExposureTime == 0) {
					ImageInfo->ExposureTime
						= (float)(1/exp(exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel)*log(2)));
				}
				break;
			case TAG_EXPOSURETIME:
				ImageInfo->ExposureTime = -1;
				break;

			case TAG_COMP_IMAGE_WIDTH:
				ImageInfo->ExifImageWidth = exif_convert_any_to_int(value_ptr, exif_rewrite_tag_format_to_unsigned(format), ImageInfo->motorola_intel);
				break;

			case TAG_FOCALPLANE_X_RES:
				ImageInfo->FocalplaneXRes = exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel);
				break;

			case TAG_SUBJECT_DISTANCE:
				/* Inidcates the distacne the autofocus camera is focused to.
				   Tends to be less accurate as distance increases. */
				ImageInfo->Distance = (float)exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel);
				break;

			case TAG_FOCALPLANE_RESOLUTION_UNIT:
				switch((int)exif_convert_any_format(value_ptr, format, ImageInfo->motorola_intel)) {
					case 1: ImageInfo->FocalplaneUnits = 25.4; break; /* inch */
					case 2:
						/* According to the information I was using, 2 measn meters.
						   But looking at the Cannon powershot's files, inches is the only
						   sensible value. */
						ImageInfo->FocalplaneUnits = 25.4;
						break;

					case 3: ImageInfo->FocalplaneUnits = 10;   break;  /* centimeter */
					case 4: ImageInfo->FocalplaneUnits = 1;    break;  /* milimeter  */
					case 5: ImageInfo->FocalplaneUnits = .001; break;  /* micrometer */
				}
				break;

			case TAG_SUB_IFD:
				if (format==TAG_FMT_IFD) {
					/* If this is called we are either in a TIFFs thumbnail or a JPEG where we cannot handle it */
					/* TIFF thumbnail: our data structure cannot store a thumbnail of a thumbnail */
					/* JPEG do we have the data area and what to do with it */
					exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Skip SUB IFD");
				}
				break;

			case TAG_MAKE:
				ImageInfo->make = estrndup(value_ptr, byte_count);
				break;
			case TAG_MODEL:
				ImageInfo->model = estrndup(value_ptr, byte_count);
				break;

			case TAG_MAKER_NOTE:
				if (!exif_process_IFD_in_MAKERNOTE(ImageInfo, value_ptr, byte_count, offset_base, IFDlength, displacement)) {
					EFREE_IF(outside);
					return FALSE;
				}
				break;

			case TAG_EXIF_IFD_POINTER:
			case TAG_GPS_IFD_POINTER:
			case TAG_INTEROP_IFD_POINTER:
				if (ReadNextIFD) {
					char *Subdir_start;
					int sub_section_index = 0;
					switch(tag) {
						case TAG_EXIF_IFD_POINTER:
#ifdef EXIF_DEBUG
							exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Found EXIF");
#endif
							ImageInfo->sections_found |= FOUND_EXIF;
							sub_section_index = SECTION_EXIF;
							break;
						case TAG_GPS_IFD_POINTER:
#ifdef EXIF_DEBUG
							exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Found GPS");
#endif
							ImageInfo->sections_found |= FOUND_GPS;
							sub_section_index = SECTION_GPS;
							break;
						case TAG_INTEROP_IFD_POINTER:
#ifdef EXIF_DEBUG
							exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Found INTEROPERABILITY");
#endif
							ImageInfo->sections_found |= FOUND_INTEROP;
							sub_section_index = SECTION_INTEROP;
							break;
					}
					Subdir_start = offset_base + php_ifd_get32u(value_ptr, ImageInfo->motorola_intel);
					if (Subdir_start < offset_base || Subdir_start > offset_base+IFDlength) {
						exif_error_docref("exif_read_data#error_ifd" EXIFERR_CC, ImageInfo, E_WARNING, "Illegal IFD Pointer");
						return FALSE;
					}
					if (!exif_process_IFD_in_JPEG(ImageInfo, Subdir_start, offset_base, IFDlength, displacement, sub_section_index, tag)) {
						return FALSE;
					}
#ifdef EXIF_DEBUG
					exif_error_docref(NULL EXIFERR_CC, ImageInfo, E_NOTICE, "Subsection %s done", exif_get_sectionname(sub_section_index));
#endif
				}
		}
	}
	exif_iif_add_tag(ImageInfo, section_index, exif_get_tagname(tag, tagname, sizeof(tagname), tag_table), tag, format, components, value_ptr, byte_count);
	EFREE_IF(outside);
	return TRUE;
}


Fix bug #78256 (heap-buffer-overflow on exif_process_user_comment)

(cherry picked from commit aeb6d13185a2ea4f1496ede2697469faed98ce05)

static void exif_iif_add_value(image_info_type *image_info, int section_index, char *name, int tag, int format, int length, void* value, size_t value_len, int motorola_intel)
{
	size_t idex;
	void *vptr, *vptr_end;
	image_info_value *info_value;
	image_info_data  *info_data;
	image_info_data  *list;

	if (length < 0) {
		return;
	}

	list = safe_erealloc(image_info->info_list[section_index].list, (image_info->info_list[section_index].count+1), sizeof(image_info_data), 0);
	image_info->info_list[section_index].list = list;

	info_data  = &image_info->info_list[section_index].list[image_info->info_list[section_index].count];
	memset(info_data, 0, sizeof(image_info_data));
	info_data->tag    = tag;
	info_data->format = format;
	info_data->length = length;
	info_data->name   = estrdup(name);
	info_value        = &info_data->value;

	switch (format) {
		case TAG_FMT_STRING:
			if (length > value_len) {
				exif_error_docref("exif_iif_add_value" EXIFERR_CC, image_info, E_WARNING, "length > value_len: %d > %zu", length, value_len);
				value = NULL;
			}
			if (value) {
				length = (int)php_strnlen(value, length);
				info_value->s = estrndup(value, length);
				info_data->length = length;
			} else {
				info_data->length = 0;
				info_value->s = estrdup("");
			}
			break;

		default:
			/* Standard says more types possible but skip them...
			 * but allow users to handle data if they know how to
			 * So not return but use type UNDEFINED
			 * return;
			 */
			info_data->tag = TAG_FMT_UNDEFINED;/* otherwise not freed from memory */
		case TAG_FMT_SBYTE:
		case TAG_FMT_BYTE:
		/* in contrast to strings bytes do not need to allocate buffer for NULL if length==0 */
			if (!length)
				break;
		case TAG_FMT_UNDEFINED:
			if (length > value_len) {
				exif_error_docref("exif_iif_add_value" EXIFERR_CC, image_info, E_WARNING, "length > value_len: %d > %zu", length, value_len);
				value = NULL;
			}
			if (value) {
				if (tag == TAG_MAKER_NOTE) {
					length = (int) php_strnlen(value, length);
				}

				/* do not recompute length here */
				info_value->s = estrndup(value, length);
				info_data->length = length;
			} else {
				info_data->length = 0;
				info_value->s = estrdup("");
			}
			break;

		case TAG_FMT_USHORT:
		case TAG_FMT_ULONG:
		case TAG_FMT_URATIONAL:
		case TAG_FMT_SSHORT:
		case TAG_FMT_SLONG:
		case TAG_FMT_SRATIONAL:
		case TAG_FMT_SINGLE:
		case TAG_FMT_DOUBLE:
			if (length==0) {
				break;
			} else
			if (length>1) {
				info_value->list = safe_emalloc(length, sizeof(image_info_value), 0);
			} else {
				info_value = &info_data->value;
			}
			vptr_end = (char *) value + value_len;
			for (idex=0,vptr=value; idex<(size_t)length; idex++,vptr=(char *) vptr + php_tiff_bytes_per_format[format]) {
				if ((char *) vptr_end - (char *) vptr < php_tiff_bytes_per_format[format]) {
					exif_error_docref("exif_iif_add_value" EXIFERR_CC, image_info, E_WARNING, "Value too short");
					break;
				}
				if (length>1) {
					info_value = &info_data->value.list[idex];
				}
				switch (format) {
					case TAG_FMT_USHORT:
						info_value->u = php_ifd_get16u(vptr, motorola_intel);
						break;

					case TAG_FMT_ULONG:
						info_value->u = php_ifd_get32u(vptr, motorola_intel);
						break;

					case TAG_FMT_URATIONAL:
						info_value->ur.num = php_ifd_get32u(vptr, motorola_intel);
						info_value->ur.den = php_ifd_get32u(4+(char *)vptr, motorola_intel);
						break;

					case TAG_FMT_SSHORT:
						info_value->i = php_ifd_get16s(vptr, motorola_intel);
						break;

					case TAG_FMT_SLONG:
						info_value->i = php_ifd_get32s(vptr, motorola_intel);
						break;

					case TAG_FMT_SRATIONAL:
						info_value->sr.num = php_ifd_get32u(vptr, motorola_intel);
						info_value->sr.den = php_ifd_get32u(4+(char *)vptr, motorola_intel);
						break;

					case TAG_FMT_SINGLE:
#ifdef EXIF_DEBUG
						php_error_docref(NULL, E_WARNING, "Found value of type single");
#endif
						info_value->f = *(float *)value;
						break;
					case TAG_FMT_DOUBLE:
#ifdef EXIF_DEBUG
						php_error_docref(NULL, E_WARNING, "Found value of type double");
#endif
						info_value->d = *(double *)value;
						break;
				}
			}
	}
	image_info->sections_found |= 1<<section_index;
	image_info->info_list[section_index].count++;
}

When PHP EXIF extension is parsing EXIF information from an image, e.g. via exif_read_data() function, in PHP versions 7.1.x below 7.1.31, 7.2.x below 7.2.21 and 7.3.x below 7.3.8 it is possible to supply it with data what will cause it to read past the allocated buffer. This may lead to information disclosure or crash.


PHP_FUNCTION(exif_thumbnail)
{
	int ret, arg_c = ZEND_NUM_ARGS();
	image_info_type ImageInfo;
	zval *stream;
	zval *z_width = NULL, *z_height = NULL, *z_imagetype = NULL;

	/* Parse arguments */
	ZEND_PARSE_PARAMETERS_START(1, 4)
		Z_PARAM_ZVAL(stream)
		Z_PARAM_OPTIONAL
		Z_PARAM_ZVAL_DEREF(z_width)
		Z_PARAM_ZVAL_DEREF(z_height)
		Z_PARAM_ZVAL_DEREF(z_imagetype)
	ZEND_PARSE_PARAMETERS_END();

	memset(&ImageInfo, 0, sizeof(ImageInfo));

	if (Z_TYPE_P(stream) == IS_RESOURCE) {
		php_stream *p_stream = NULL;

		php_stream_from_res(p_stream, Z_RES_P(stream));

		ret = exif_read_from_stream(&ImageInfo, p_stream, 1, 0);
	} else {
		convert_to_string(stream);

		if (!Z_STRLEN_P(stream)) {
			exif_error_docref(NULL EXIFERR_CC, &ImageInfo, E_WARNING, "Filename cannot be empty");

			RETURN_FALSE;
		}

		ret = exif_read_from_file(&ImageInfo, Z_STRVAL_P(stream), 1, 0);
	}

	if (ret == FALSE) {
		exif_discard_imageinfo(&ImageInfo);
		RETURN_FALSE;
	}

#ifdef EXIF_DEBUG
	exif_error_docref(NULL EXIFERR_CC, &ImageInfo, E_NOTICE, "Thumbnail data %d %d %d, %d x %d", ImageInfo.Thumbnail.data, ImageInfo.Thumbnail.size, ImageInfo.Thumbnail.filetype, ImageInfo.Thumbnail.width, ImageInfo.Thumbnail.height);
#endif
	if (!ImageInfo.Thumbnail.data || !ImageInfo.Thumbnail.size) {
		exif_discard_imageinfo(&ImageInfo);
		RETURN_FALSE;
	}

#ifdef EXIF_DEBUG
	exif_error_docref(NULL EXIFERR_CC, &ImageInfo, E_NOTICE, "Returning thumbnail(%d)", ImageInfo.Thumbnail.size);
#endif

	ZVAL_STRINGL(return_value, ImageInfo.Thumbnail.data, ImageInfo.Thumbnail.size);
	if (arg_c >= 3) {
		if (!ImageInfo.Thumbnail.width || !ImageInfo.Thumbnail.height) {
			if (!exif_scan_thumbnail(&ImageInfo)) {
				ImageInfo.Thumbnail.width = ImageInfo.Thumbnail.height = 0;
			}
		}
		zval_ptr_dtor(z_width);
		zval_ptr_dtor(z_height);
		ZVAL_LONG(z_width,  ImageInfo.Thumbnail.width);
		ZVAL_LONG(z_height, ImageInfo.Thumbnail.height);
	}
	if (arg_c >= 4)	{
		zval_ptr_dtor(z_imagetype);
		ZVAL_LONG(z_imagetype, ImageInfo.Thumbnail.filetype);
	}

#ifdef EXIF_DEBUG
	exif_error_docref(NULL EXIFERR_CC, &ImageInfo, E_NOTICE, "Discarding info");
#endif

	exif_discard_imageinfo(&ImageInfo);

#ifdef EXIF_DEBUG
	php_error_docref1(NULL, (Z_TYPE_P(stream) == IS_RESOURCE ? "<stream>" : Z_STRVAL_P(stream)), E_NOTICE, "Done");
#endif
}


hw/nvme: fix CVE-2021-3929

This fixes CVE-2021-3929 "locally" by denying DMA to the iomem of the
device itself. This still allows DMA to MMIO regions of other devices
(e.g. doing P2P DMA to the controller memory buffer of another NVMe
device).

Fixes: CVE-2021-3929
Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>

static inline bool nvme_addr_is_iomem(NvmeCtrl *n, hwaddr addr)
{
    hwaddr hi, lo;

    /*
     * The purpose of this check is to guard against invalid "local" access to
     * the iomem (i.e. controller registers). Thus, we check against the range
     * covered by the 'bar0' MemoryRegion since that is currently composed of
     * two subregions (the NVMe "MBAR" and the MSI-X table/pba). Note, however,
     * that if the device model is ever changed to allow the CMB to be located
     * in BAR0 as well, then this must be changed.
     */
    lo = n->bar0.addr;
    hi = lo + int128_get64(n->bar0.size);

    return addr >= lo && addr < hi;
}


static uint16_t nvme_tx(NvmeCtrl *n, NvmeSg *sg, uint8_t *ptr, uint32_t len,
                        NvmeTxDirection dir)
{
    assert(sg->flags & NVME_SG_ALLOC);

    if (sg->flags & NVME_SG_DMA) {
        const MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
        dma_addr_t residual;

        if (dir == NVME_TX_DIRECTION_TO_DEVICE) {
            dma_buf_write(ptr, len, &residual, &sg->qsg, attrs);
        } else {
            dma_buf_read(ptr, len, &residual, &sg->qsg, attrs);
        }

        if (unlikely(residual)) {
            trace_pci_nvme_err_invalid_dma();
            return NVME_INVALID_FIELD | NVME_DNR;
        }
    } else {
        size_t bytes;

        if (dir == NVME_TX_DIRECTION_TO_DEVICE) {
            bytes = qemu_iovec_to_buf(&sg->iov, 0, ptr, len);
        } else {
            bytes = qemu_iovec_from_buf(&sg->iov, 0, ptr, len);
        }

        if (unlikely(bytes != len)) {
            trace_pci_nvme_err_invalid_dma();
            return NVME_INVALID_FIELD | NVME_DNR;
        }
    }

    return NVME_SUCCESS;
}


static uint16_t nvme_map_addr(NvmeCtrl *n, NvmeSg *sg, hwaddr addr, size_t len)
{
    bool cmb = false, pmr = false;

    if (!len) {
        return NVME_SUCCESS;
    }

    trace_pci_nvme_map_addr(addr, len);

    if (nvme_addr_is_iomem(n, addr)) {
        return NVME_DATA_TRAS_ERROR;
    }

    if (nvme_addr_is_cmb(n, addr)) {
        cmb = true;
    } else if (nvme_addr_is_pmr(n, addr)) {
        pmr = true;
    }

    if (cmb || pmr) {
        if (sg->flags & NVME_SG_DMA) {
            return NVME_INVALID_USE_OF_CMB | NVME_DNR;
        }

        if (sg->iov.niov + 1 > IOV_MAX) {
            goto max_mappings_exceeded;
        }

        if (cmb) {
            return nvme_map_addr_cmb(n, &sg->iov, addr, len);
        } else {
            return nvme_map_addr_pmr(n, &sg->iov, addr, len);
        }
    }

    if (!(sg->flags & NVME_SG_DMA)) {
        return NVME_INVALID_USE_OF_CMB | NVME_DNR;
    }

    if (sg->qsg.nsg + 1 > IOV_MAX) {
        goto max_mappings_exceeded;
    }

    qemu_sglist_add(&sg->qsg, addr, len);

    return NVME_SUCCESS;

max_mappings_exceeded:
    NVME_GUEST_ERR(pci_nvme_ub_too_many_mappings,
                   "number of mappings exceed 1024");
    return NVME_INTERNAL_DEV_ERROR | NVME_DNR;
}


do_epoll_ctl(): clean the failure exits up a bit

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

static int ep_modify(struct eventpoll *ep, struct epitem *epi,
		     const struct epoll_event *event)
{
	int pwake = 0;
	poll_table pt;

	lockdep_assert_irqs_enabled();

	init_poll_funcptr(&pt, NULL);

	/*
	 * Set the new event interest mask before calling f_op->poll();
	 * otherwise we might miss an event that happens between the
	 * f_op->poll() call and the new event set registering.
	 */
	epi->event.events = event->events; /* need barrier below */
	epi->event.data = event->data; /* protected by mtx */
	if (epi->event.events & EPOLLWAKEUP) {
		if (!ep_has_wakeup_source(epi))
			ep_create_wakeup_source(epi);
	} else if (ep_has_wakeup_source(epi)) {
		ep_destroy_wakeup_source(epi);
	}

	/*
	 * The following barrier has two effects:
	 *
	 * 1) Flush epi changes above to other CPUs.  This ensures
	 *    we do not miss events from ep_poll_callback if an
	 *    event occurs immediately after we call f_op->poll().
	 *    We need this because we did not take ep->lock while
	 *    changing epi above (but ep_poll_callback does take
	 *    ep->lock).
	 *
	 * 2) We also need to ensure we do not miss _past_ events
	 *    when calling f_op->poll().  This barrier also
	 *    pairs with the barrier in wq_has_sleeper (see
	 *    comments for wq_has_sleeper).
	 *
	 * This barrier will now guarantee ep_poll_callback or f_op->poll
	 * (or both) will notice the readiness of an item.
	 */
	smp_mb();

	/*
	 * Get current event bits. We can safely use the file* here because
	 * its usage count has been increased by the caller of this function.
	 * If the item is "hot" and it is not registered inside the ready
	 * list, push it inside.
	 */
	if (ep_item_poll(epi, &pt, 1)) {
		write_lock_irq(&ep->lock);
		if (!ep_is_linked(epi)) {
			list_add_tail(&epi->rdllink, &ep->rdllist);
			ep_pm_stay_awake(epi);

			/* Notify waiting tasks that events are available */
			if (waitqueue_active(&ep->wq))
				wake_up(&ep->wq);
			if (waitqueue_active(&ep->poll_wait))
				pwake++;
		}
		write_unlock_irq(&ep->lock);
	}

	/* We have to call this outside the lock */
	if (pwake)
		ep_poll_safewake(ep, NULL);

	return 0;
}

In do_epoll_ctl and ep_loop_check_proc of eventpoll.c, there is a possible use after free due to a logic error. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-147802478References: Upstream kernel


static int do_epoll_wait(int epfd, struct epoll_event __user *events,
			 int maxevents, int timeout)
{
	int error;
	struct fd f;
	struct eventpoll *ep;

	/* The maximum number of event must be greater than zero */
	if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
		return -EINVAL;

	/* Verify that the area passed by the user is writeable */
	if (!access_ok(events, maxevents * sizeof(struct epoll_event)))
		return -EFAULT;

	/* Get the "struct file *" for the eventpoll file */
	f = fdget(epfd);
	if (!f.file)
		return -EBADF;

	/*
	 * We have to check that the file structure underneath the fd
	 * the user passed to us _is_ an eventpoll file.
	 */
	error = -EINVAL;
	if (!is_file_epoll(f.file))
		goto error_fput;

	/*
	 * At this point it is safe to assume that the "private_data" contains
	 * our own data structure.
	 */
	ep = f.file->private_data;

	/* Time to fish for events ... */
	error = ep_poll(ep, events, maxevents, timeout);

error_fput:
	fdput(f);
	return error;
}


static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p)
{
	return container_of(p, struct eppoll_entry, wait)->base;
}


static int ep_create_wakeup_source(struct epitem *epi)
{
	const char *name;
	struct wakeup_source *ws;

	if (!epi->ep->ws) {
		epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
		if (!epi->ep->ws)
			return -ENOMEM;
	}

	name = epi->ffd.file->f_path.dentry->d_name.name;
	ws = wakeup_source_register(NULL, name);

	if (!ws)
		return -ENOMEM;
	rcu_assign_pointer(epi->ws, ws);

	return 0;
}


SYSCALL_DEFINE1(epoll_create, int, size)
{
	if (size <= 0)
		return -EINVAL;

	return do_epoll_create(0);
}


static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
{
	wake_up_poll(&ep->poll_wait, EPOLLIN);
}


SYSCALL_DEFINE1(epoll_create1, int, flags)
{
	return do_epoll_create(flags);
}


static inline int ep_events_available(struct eventpoll *ep)
{
	return !list_empty_careful(&ep->rdllist) ||
		READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR;
}


static inline void ep_busy_loop(struct eventpoll *ep, int nonblock)
{
}


static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
		     struct file *tfile, int fd, int full_check)
{
	int error, pwake = 0;
	__poll_t revents;
	long user_watches;
	struct epitem *epi;
	struct ep_pqueue epq;

	lockdep_assert_irqs_enabled();

	user_watches = atomic_long_read(&ep->user->epoll_watches);
	if (unlikely(user_watches >= max_user_watches))
		return -ENOSPC;
	if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
		return -ENOMEM;

	/* Item initialization follow here ... */
	INIT_LIST_HEAD(&epi->rdllink);
	INIT_LIST_HEAD(&epi->fllink);
	INIT_LIST_HEAD(&epi->pwqlist);
	epi->ep = ep;
	ep_set_ffd(&epi->ffd, tfile, fd);
	epi->event = *event;
	epi->nwait = 0;
	epi->next = EP_UNACTIVE_PTR;
	if (epi->event.events & EPOLLWAKEUP) {
		error = ep_create_wakeup_source(epi);
		if (error)
			goto error_create_wakeup_source;
	} else {
		RCU_INIT_POINTER(epi->ws, NULL);
	}

	/* Initialize the poll table using the queue callback */
	epq.epi = epi;
	init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);

	/*
	 * Attach the item to the poll hooks and get current event bits.
	 * We can safely use the file* here because its usage count has
	 * been increased by the caller of this function. Note that after
	 * this operation completes, the poll callback can start hitting
	 * the new item.
	 */
	revents = ep_item_poll(epi, &epq.pt, 1);

	/*
	 * We have to check if something went wrong during the poll wait queue
	 * install process. Namely an allocation for a wait queue failed due
	 * high memory pressure.
	 */
	error = -ENOMEM;
	if (epi->nwait < 0)
		goto error_unregister;

	/* Add the current item to the list of active epoll hook for this file */
	spin_lock(&tfile->f_lock);
	list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
	spin_unlock(&tfile->f_lock);

	/*
	 * Add the current item to the RB tree. All RB tree operations are
	 * protected by "mtx", and ep_insert() is called with "mtx" held.
	 */
	ep_rbtree_insert(ep, epi);

	/* now check if we've created too many backpaths */
	error = -EINVAL;
	if (full_check && reverse_path_check())
		goto error_remove_epi;

	/* We have to drop the new item inside our item list to keep track of it */
	write_lock_irq(&ep->lock);

	/* record NAPI ID of new item if present */
	ep_set_busy_poll_napi_id(epi);

	/* If the file is already "ready" we drop it inside the ready list */
	if (revents && !ep_is_linked(epi)) {
		list_add_tail(&epi->rdllink, &ep->rdllist);
		ep_pm_stay_awake(epi);

		/* Notify waiting tasks that events are available */
		if (waitqueue_active(&ep->wq))
			wake_up(&ep->wq);
		if (waitqueue_active(&ep->poll_wait))
			pwake++;
	}

	write_unlock_irq(&ep->lock);

	atomic_long_inc(&ep->user->epoll_watches);

	/* We have to call this outside the lock */
	if (pwake)
		ep_poll_safewake(ep, NULL);

	return 0;

error_remove_epi:
	spin_lock(&tfile->f_lock);
	list_del_rcu(&epi->fllink);
	spin_unlock(&tfile->f_lock);

	rb_erase_cached(&epi->rbn, &ep->rbr);

error_unregister:
	ep_unregister_pollwait(ep, epi);

	/*
	 * We need to do this because an event could have been arrived on some
	 * allocated wait queue. Note that we don't care about the ep->ovflist
	 * list, since that is used/cleaned only inside a section bound by "mtx".
	 * And ep_insert() is called with "mtx" held.
	 */
	write_lock_irq(&ep->lock);
	if (ep_is_linked(epi))
		list_del_init(&epi->rdllink);
	write_unlock_irq(&ep->lock);

	wakeup_source_unregister(ep_wakeup_source(epi));

error_create_wakeup_source:
	kmem_cache_free(epi_cache, epi);

	return error;
}


static __poll_t ep_scan_ready_list(struct eventpoll *ep,
			      __poll_t (*sproc)(struct eventpoll *,
					   struct list_head *, void *),
			      void *priv, int depth, bool ep_locked)
{
	__poll_t res;
	struct epitem *epi, *nepi;
	LIST_HEAD(txlist);

	lockdep_assert_irqs_enabled();

	/*
	 * We need to lock this because we could be hit by
	 * eventpoll_release_file() and epoll_ctl().
	 */

	if (!ep_locked)
		mutex_lock_nested(&ep->mtx, depth);

	/*
	 * Steal the ready list, and re-init the original one to the
	 * empty list. Also, set ep->ovflist to NULL so that events
	 * happening while looping w/out locks, are not lost. We cannot
	 * have the poll callback to queue directly on ep->rdllist,
	 * because we want the "sproc" callback to be able to do it
	 * in a lockless way.
	 */
	write_lock_irq(&ep->lock);
	list_splice_init(&ep->rdllist, &txlist);
	WRITE_ONCE(ep->ovflist, NULL);
	write_unlock_irq(&ep->lock);

	/*
	 * Now call the callback function.
	 */
	res = (*sproc)(ep, &txlist, priv);

	write_lock_irq(&ep->lock);
	/*
	 * During the time we spent inside the "sproc" callback, some
	 * other events might have been queued by the poll callback.
	 * We re-insert them inside the main ready-list here.
	 */
	for (nepi = READ_ONCE(ep->ovflist); (epi = nepi) != NULL;
	     nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
		/*
		 * We need to check if the item is already in the list.
		 * During the "sproc" callback execution time, items are
		 * queued into ->ovflist but the "txlist" might already
		 * contain them, and the list_splice() below takes care of them.
		 */
		if (!ep_is_linked(epi)) {
			/*
			 * ->ovflist is LIFO, so we have to reverse it in order
			 * to keep in FIFO.
			 */
			list_add(&epi->rdllink, &ep->rdllist);
			ep_pm_stay_awake(epi);
		}
	}
	/*
	 * We need to set back ep->ovflist to EP_UNACTIVE_PTR, so that after
	 * releasing the lock, events will be queued in the normal way inside
	 * ep->rdllist.
	 */
	WRITE_ONCE(ep->ovflist, EP_UNACTIVE_PTR);

	/*
	 * Quickly re-inject items left on "txlist".
	 */
	list_splice(&txlist, &ep->rdllist);
	__pm_relax(ep->ws);
	write_unlock_irq(&ep->lock);

	if (!ep_locked)
		mutex_unlock(&ep->mtx);

	return res;
}


static int ep_loop_check(struct eventpoll *ep, struct file *file)
{
	int ret;
	struct eventpoll *ep_cur, *ep_next;

	ret = ep_call_nested(&poll_loop_ncalls,
			      ep_loop_check_proc, file, ep, current);
	/* clear visited list */
	list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
							visited_list_link) {
		ep_cur->visited = 0;
		list_del(&ep_cur->visited_list_link);
	}
	return ret;
}


struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd,
				     unsigned long toff)
{
	struct file *file_raw;
	struct eventpoll *ep;
	struct epitem *epi;

	if (!is_file_epoll(file))
		return ERR_PTR(-EINVAL);

	ep = file->private_data;

	mutex_lock(&ep->mtx);
	epi = ep_find_tfd(ep, tfd, toff);
	if (epi)
		file_raw = epi->ffd.file;
	else
		file_raw = ERR_PTR(-ENOENT);
	mutex_unlock(&ep->mtx);

	return file_raw;
}


static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt,
				 int depth)
{
	struct eventpoll *ep;
	bool locked;

	pt->_key = epi->event.events;
	if (!is_file_epoll(epi->ffd.file))
		return vfs_poll(epi->ffd.file, pt) & epi->event.events;

	ep = epi->ffd.file->private_data;
	poll_wait(epi->ffd.file, &ep->poll_wait, pt);
	locked = pt && (pt->_qproc == ep_ptable_queue_proc);

	return ep_scan_ready_list(epi->ffd.file->private_data,
				  ep_read_events_proc, &depth, depth,
				  locked) & epi->event.events;
}


static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_entry_t *p)
{
	return container_of(p, struct eppoll_entry, wait);
}


SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
		int, maxevents, int, timeout)
{
	return do_epoll_wait(epfd, events, maxevents, timeout);
}


static int ep_alloc(struct eventpoll **pep)
{
	int error;
	struct user_struct *user;
	struct eventpoll *ep;

	user = get_current_user();
	error = -ENOMEM;
	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
	if (unlikely(!ep))
		goto free_uid;

	mutex_init(&ep->mtx);
	rwlock_init(&ep->lock);
	init_waitqueue_head(&ep->wq);
	init_waitqueue_head(&ep->poll_wait);
	INIT_LIST_HEAD(&ep->rdllist);
	ep->rbr = RB_ROOT_CACHED;
	ep->ovflist = EP_UNACTIVE_PTR;
	ep->user = user;

	*pep = ep;

	return 0;

free_uid:
	free_uid(user);
	return error;
}


static int ep_call_nested(struct nested_calls *ncalls,
			  int (*nproc)(void *, void *, int), void *priv,
			  void *cookie, void *ctx)
{
	int error, call_nests = 0;
	unsigned long flags;
	struct list_head *lsthead = &ncalls->tasks_call_list;
	struct nested_call_node *tncur;
	struct nested_call_node tnode;

	spin_lock_irqsave(&ncalls->lock, flags);

	/*
	 * Try to see if the current task is already inside this wakeup call.
	 * We use a list here, since the population inside this set is always
	 * very much limited.
	 */
	list_for_each_entry(tncur, lsthead, llink) {
		if (tncur->ctx == ctx &&
		    (tncur->cookie == cookie || ++call_nests > EP_MAX_NESTS)) {
			/*
			 * Ops ... loop detected or maximum nest level reached.
			 * We abort this wake by breaking the cycle itself.
			 */
			error = -1;
			goto out_unlock;
		}
	}

	/* Add the current task and cookie to the list */
	tnode.ctx = ctx;
	tnode.cookie = cookie;
	list_add(&tnode.llink, lsthead);

	spin_unlock_irqrestore(&ncalls->lock, flags);

	/* Call the nested function */
	error = (*nproc)(priv, cookie, call_nests);

	/* Remove the current task from the list */
	spin_lock_irqsave(&ncalls->lock, flags);
	list_del(&tnode.llink);
out_unlock:
	spin_unlock_irqrestore(&ncalls->lock, flags);

	return error;
}


static int ep_send_events(struct eventpoll *ep,
			  struct epoll_event __user *events, int maxevents)
{
	struct ep_send_events_data esed;

	esed.maxevents = maxevents;
	esed.events = events;

	ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0, false);
	return esed.res;
}


static void ep_show_fdinfo(struct seq_file *m, struct file *f)
{
	struct eventpoll *ep = f->private_data;
	struct rb_node *rbp;

	mutex_lock(&ep->mtx);
	for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
		struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
		struct inode *inode = file_inode(epi->ffd.file);

		seq_printf(m, "tfd: %8d events: %8x data: %16llx "
			   " pos:%lli ino:%lx sdev:%x\n",
			   epi->ffd.fd, epi->event.events,
			   (long long)epi->event.data,
			   (long long)epi->ffd.file->f_pos,
			   inode->i_ino, inode->i_sb->s_dev);
		if (seq_has_overflowed(m))
			break;
	}
	mutex_unlock(&ep->mtx);
}


static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
{
	int kcmp;
	struct rb_node **p = &ep->rbr.rb_root.rb_node, *parent = NULL;
	struct epitem *epic;
	bool leftmost = true;

	while (*p) {
		parent = *p;
		epic = rb_entry(parent, struct epitem, rbn);
		kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
		if (kcmp > 0) {
			p = &parent->rb_right;
			leftmost = false;
		} else
			p = &parent->rb_left;
	}
	rb_link_node(&epi->rbn, parent, p);
	rb_insert_color_cached(&epi->rbn, &ep->rbr, leftmost);
}


static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
				   bool nonblock)
{
	if (!nonblock) {
		mutex_lock_nested(mutex, depth);
		return 0;
	}
	if (mutex_trylock(mutex))
		return 0;
	return -EAGAIN;
}


static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)
{
	int error = 0;
	struct file *file = priv;
	struct file *child_file;
	struct epitem *epi;

	/* CTL_DEL can remove links here, but that can't increase our count */
	rcu_read_lock();
	list_for_each_entry_rcu(epi, &file->f_ep_links, fllink) {
		child_file = epi->ep->file;
		if (is_file_epoll(child_file)) {
			if (list_empty(&child_file->f_ep_links)) {
				if (path_count_inc(call_nests)) {
					error = -1;
					break;
				}
			} else {
				error = ep_call_nested(&poll_loop_ncalls,
							reverse_path_check_proc,
							child_file, child_file,
							current);
			}
			if (error != 0)
				break;
		} else {
			printk(KERN_ERR "reverse_path_check_proc: "
				"file is not an ep!\n");
		}
	}
	rcu_read_unlock();
	return error;
}


SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
		int, maxevents, int, timeout, const sigset_t __user *, sigmask,
		size_t, sigsetsize)
{
	int error;

	/*
	 * If the caller wants a certain signal mask to be set during the wait,
	 * we apply it here.
	 */
	error = set_user_sigmask(sigmask, sigsetsize);
	if (error)
		return error;

	error = do_epoll_wait(epfd, events, maxevents, timeout);
	restore_saved_sigmask_unless(error == -EINTR);

	return error;
}


COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
			struct epoll_event __user *, events,
			int, maxevents, int, timeout,
			const compat_sigset_t __user *, sigmask,
			compat_size_t, sigsetsize)
{
	long err;

	/*
	 * If the caller wants a certain signal mask to be set during the wait,
	 * we apply it here.
	 */
	err = set_compat_user_sigmask(sigmask, sigsetsize);
	if (err)
		return err;

	err = do_epoll_wait(epfd, events, maxevents, timeout);
	restore_saved_sigmask_unless(err == -EINTR);

	return err;
}


static int __init eventpoll_init(void)
{
	struct sysinfo si;

	si_meminfo(&si);
	/*
	 * Allows top 4% of lomem to be allocated for epoll watches (per user).
	 */
	max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
		EP_ITEM_COST;
	BUG_ON(max_user_watches < 0);

	/*
	 * Initialize the structure used to perform epoll file descriptor
	 * inclusion loops checks.
	 */
	ep_nested_calls_init(&poll_loop_ncalls);

	/*
	 * We can have many thousands of epitems, so prevent this from
	 * using an extra cache line on 64-bit (and smaller) CPUs
	 */
	BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128);

	/* Allocates slab cache used to allocate "struct epitem" items */
	epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);

	/* Allocates slab cache used to allocate "struct eppoll_entry" */
	pwq_cache = kmem_cache_create("eventpoll_pwq",
		sizeof(struct eppoll_entry), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL);

	return 0;
}


static void ep_free(struct eventpoll *ep)
{
	struct rb_node *rbp;
	struct epitem *epi;

	/* We need to release all tasks waiting for these file */
	if (waitqueue_active(&ep->poll_wait))
		ep_poll_safewake(ep, NULL);

	/*
	 * We need to lock this because we could be hit by
	 * eventpoll_release_file() while we're freeing the "struct eventpoll".
	 * We do not need to hold "ep->mtx" here because the epoll file
	 * is on the way to be removed and no one has references to it
	 * anymore. The only hit might come from eventpoll_release_file() but
	 * holding "epmutex" is sufficient here.
	 */
	mutex_lock(&epmutex);

	/*
	 * Walks through the whole tree by unregistering poll callbacks.
	 */
	for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
		epi = rb_entry(rbp, struct epitem, rbn);

		ep_unregister_pollwait(ep, epi);
		cond_resched();
	}

	/*
	 * Walks through the whole tree by freeing each "struct epitem". At this
	 * point we are sure no poll callbacks will be lingering around, and also by
	 * holding "epmutex" we can be sure that no file cleanup code will hit
	 * us during this operation. So we can avoid the lock on "ep->lock".
	 * We do not need to lock ep->mtx, either, we only do it to prevent
	 * a lockdep warning.
	 */
	mutex_lock(&ep->mtx);
	while ((rbp = rb_first_cached(&ep->rbr)) != NULL) {
		epi = rb_entry(rbp, struct epitem, rbn);
		ep_remove(ep, epi);
		cond_resched();
	}
	mutex_unlock(&ep->mtx);

	mutex_unlock(&epmutex);
	mutex_destroy(&ep->mtx);
	free_uid(ep->user);
	wakeup_source_unregister(ep->ws);
	kfree(ep);
}


static void clear_tfile_check_list(void)
{
	struct file *file;

	/* first clear the tfile_check_list */
	while (!list_empty(&tfile_check_list)) {
		file = list_first_entry(&tfile_check_list, struct file,
					f_tfile_llink);
		list_del_init(&file->f_tfile_llink);
		fput(file);
	}
	INIT_LIST_HEAD(&tfile_check_list);
}


static __poll_t ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
			       void *priv)
{
	struct ep_send_events_data *esed = priv;
	__poll_t revents;
	struct epitem *epi, *tmp;
	struct epoll_event __user *uevent = esed->events;
	struct wakeup_source *ws;
	poll_table pt;

	init_poll_funcptr(&pt, NULL);
	esed->res = 0;

	/*
	 * We can loop without lock because we are passed a task private list.
	 * Items cannot vanish during the loop because ep_scan_ready_list() is
	 * holding "mtx" during this call.
	 */
	lockdep_assert_held(&ep->mtx);

	list_for_each_entry_safe(epi, tmp, head, rdllink) {
		if (esed->res >= esed->maxevents)
			break;

		/*
		 * Activate ep->ws before deactivating epi->ws to prevent
		 * triggering auto-suspend here (in case we reactive epi->ws
		 * below).
		 *
		 * This could be rearranged to delay the deactivation of epi->ws
		 * instead, but then epi->ws would temporarily be out of sync
		 * with ep_is_linked().
		 */
		ws = ep_wakeup_source(epi);
		if (ws) {
			if (ws->active)
				__pm_stay_awake(ep->ws);
			__pm_relax(ws);
		}

		list_del_init(&epi->rdllink);

		/*
		 * If the event mask intersect the caller-requested one,
		 * deliver the event to userspace. Again, ep_scan_ready_list()
		 * is holding ep->mtx, so no operations coming from userspace
		 * can change the item.
		 */
		revents = ep_item_poll(epi, &pt, 1);
		if (!revents)
			continue;

		if (__put_user(revents, &uevent->events) ||
		    __put_user(epi->event.data, &uevent->data)) {
			list_add(&epi->rdllink, head);
			ep_pm_stay_awake(epi);
			if (!esed->res)
				esed->res = -EFAULT;
			return 0;
		}
		esed->res++;
		uevent++;
		if (epi->event.events & EPOLLONESHOT)
			epi->event.events &= EP_PRIVATE_BITS;
		else if (!(epi->event.events & EPOLLET)) {
			/*
			 * If this file has been added with Level
			 * Trigger mode, we need to insert back inside
			 * the ready list, so that the next call to
			 * epoll_wait() will check again the events
			 * availability. At this point, no one can insert
			 * into ep->rdllist besides us. The epoll_ctl()
			 * callers are locked out by
			 * ep_scan_ready_list() holding "mtx" and the
			 * poll callback will queue them in ep->ovflist.
			 */
			list_add_tail(&epi->rdllink, &ep->rdllist);
			ep_pm_stay_awake(epi);
		}
	}

	return 0;
}


static inline bool list_add_tail_lockless(struct list_head *new,
					  struct list_head *head)
{
	struct list_head *prev;

	/*
	 * This is simple 'new->next = head' operation, but cmpxchg()
	 * is used in order to detect that same element has been just
	 * added to the list from another CPU: the winner observes
	 * new->next == new.
	 */
	if (cmpxchg(&new->next, new, head) != new)
		return false;

	/*
	 * Initially ->next of a new element must be updated with the head
	 * (we are inserting to the tail) and only then pointers are atomically
	 * exchanged.  XCHG guarantees memory ordering, thus ->next should be
	 * updated before pointers are actually swapped and pointers are
	 * swapped before prev->next is updated.
	 */

	prev = xchg(&head->prev, new);

	/*
	 * It is safe to modify prev->next and new->prev, because a new element
	 * is added only to the tail and new->next is updated before XCHG.
	 */

	prev->next = new;
	new->prev = prev;

	return true;
}


static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
		   int maxevents, long timeout)
{
	int res = 0, eavail, timed_out = 0;
	u64 slack = 0;
	wait_queue_entry_t wait;
	ktime_t expires, *to = NULL;

	lockdep_assert_irqs_enabled();

	if (timeout > 0) {
		struct timespec64 end_time = ep_set_mstimeout(timeout);

		slack = select_estimate_accuracy(&end_time);
		to = &expires;
		*to = timespec64_to_ktime(end_time);
	} else if (timeout == 0) {
		/*
		 * Avoid the unnecessary trip to the wait queue loop, if the
		 * caller specified a non blocking operation. We still need
		 * lock because we could race and not see an epi being added
		 * to the ready list while in irq callback. Thus incorrectly
		 * returning 0 back to userspace.
		 */
		timed_out = 1;

		write_lock_irq(&ep->lock);
		eavail = ep_events_available(ep);
		write_unlock_irq(&ep->lock);

		goto send_events;
	}

fetch_events:

	if (!ep_events_available(ep))
		ep_busy_loop(ep, timed_out);

	eavail = ep_events_available(ep);
	if (eavail)
		goto send_events;

	/*
	 * Busy poll timed out.  Drop NAPI ID for now, we can add
	 * it back in when we have moved a socket with a valid NAPI
	 * ID onto the ready list.
	 */
	ep_reset_busy_poll_napi_id(ep);

	do {
		/*
		 * Internally init_wait() uses autoremove_wake_function(),
		 * thus wait entry is removed from the wait queue on each
		 * wakeup. Why it is important? In case of several waiters
		 * each new wakeup will hit the next waiter, giving it the
		 * chance to harvest new event. Otherwise wakeup can be
		 * lost. This is also good performance-wise, because on
		 * normal wakeup path no need to call __remove_wait_queue()
		 * explicitly, thus ep->lock is not taken, which halts the
		 * event delivery.
		 */
		init_wait(&wait);

		write_lock_irq(&ep->lock);
		/*
		 * Barrierless variant, waitqueue_active() is called under
		 * the same lock on wakeup ep_poll_callback() side, so it
		 * is safe to avoid an explicit barrier.
		 */
		__set_current_state(TASK_INTERRUPTIBLE);

		/*
		 * Do the final check under the lock. ep_scan_ready_list()
		 * plays with two lists (->rdllist and ->ovflist) and there
		 * is always a race when both lists are empty for short
		 * period of time although events are pending, so lock is
		 * important.
		 */
		eavail = ep_events_available(ep);
		if (!eavail) {
			if (signal_pending(current))
				res = -EINTR;
			else
				__add_wait_queue_exclusive(&ep->wq, &wait);
		}
		write_unlock_irq(&ep->lock);

		if (eavail || res)
			break;

		if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) {
			timed_out = 1;
			break;
		}

		/* We were woken up, thus go and try to harvest some events */
		eavail = 1;

	} while (0);

	__set_current_state(TASK_RUNNING);

	if (!list_empty_careful(&wait.entry)) {
		write_lock_irq(&ep->lock);
		__remove_wait_queue(&ep->wq, &wait);
		write_unlock_irq(&ep->lock);
	}

send_events:
	if (fatal_signal_pending(current)) {
		/*
		 * Always short-circuit for fatal signals to allow
		 * threads to make a timely exit without the chance of
		 * finding more events available and fetching
		 * repeatedly.
		 */
		res = -EINTR;
	}
	/*
	 * Try to transfer events to user space. In case we get 0 events and
	 * there's still timeout left over, we go trying again in search of
	 * more luck.
	 */
	if (!res && eavail &&
	    !(res = ep_send_events(ep, events, maxevents)) && !timed_out)
		goto fetch_events;

	return res;
}


static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff)
{
	struct rb_node *rbp;
	struct epitem *epi;

	for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
		epi = rb_entry(rbp, struct epitem, rbn);
		if (epi->ffd.fd == tfd) {
			if (toff == 0)
				return epi;
			else
				toff--;
		}
		cond_resched();
	}

	return NULL;
}


static noinline void ep_destroy_wakeup_source(struct epitem *epi)
{
	struct wakeup_source *ws = ep_wakeup_source(epi);

	RCU_INIT_POINTER(epi->ws, NULL);

	/*
	 * wait for ep_pm_stay_awake_rcu to finish, synchronize_rcu is
	 * used internally by wakeup_source_remove, too (called by
	 * wakeup_source_unregister), so we cannot use call_rcu
	 */
	synchronize_rcu();
	wakeup_source_unregister(ws);
}


static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
{
	struct wakeup_source *ws;

	rcu_read_lock();
	ws = rcu_dereference(epi->ws);
	if (ws)
		__pm_stay_awake(ws);
	rcu_read_unlock();
}


static void ep_busy_loop(struct eventpoll *ep, int nonblock)
{
	unsigned int napi_id = READ_ONCE(ep->napi_id);

	if ((napi_id >= MIN_NAPI_ID) && net_busy_loop_on())
		napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep);
}


static inline void ep_pm_stay_awake(struct epitem *epi)
{
	struct wakeup_source *ws = ep_wakeup_source(epi);

	if (ws)
		__pm_stay_awake(ws);
}


static int reverse_path_check(void)
{
	int error = 0;
	struct file *current_file;

	/* let's call this for all tfiles */
	list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {
		path_count_init();
		error = ep_call_nested(&poll_loop_ncalls,
					reverse_path_check_proc, current_file,
					current_file, current);
		if (error)
			break;
	}
	return error;
}


static inline int ep_is_linked(struct epitem *epi)
{
	return !list_empty(&epi->rdllink);
}


static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
{
	int kcmp;
	struct rb_node *rbp;
	struct epitem *epi, *epir = NULL;
	struct epoll_filefd ffd;

	ep_set_ffd(&ffd, file, fd);
	for (rbp = ep->rbr.rb_root.rb_node; rbp; ) {
		epi = rb_entry(rbp, struct epitem, rbn);
		kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
		if (kcmp > 0)
			rbp = rbp->rb_right;
		else if (kcmp < 0)
			rbp = rbp->rb_left;
		else {
			epir = epi;
			break;
		}
	}

	return epir;
}


static inline bool ep_has_wakeup_source(struct epitem *epi)
{
	return rcu_access_pointer(epi->ws) ? true : false;
}


static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
{
}


int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
		 bool nonblock)
{
	int error;
	int full_check = 0;
	struct fd f, tf;
	struct eventpoll *ep;
	struct epitem *epi;
	struct eventpoll *tep = NULL;

	error = -EBADF;
	f = fdget(epfd);
	if (!f.file)
		goto error_return;

	/* Get the "struct file *" for the target file */
	tf = fdget(fd);
	if (!tf.file)
		goto error_fput;

	/* The target file descriptor must support poll */
	error = -EPERM;
	if (!file_can_poll(tf.file))
		goto error_tgt_fput;

	/* Check if EPOLLWAKEUP is allowed */
	if (ep_op_has_event(op))
		ep_take_care_of_epollwakeup(epds);

	/*
	 * We have to check that the file structure underneath the file descriptor
	 * the user passed to us _is_ an eventpoll file. And also we do not permit
	 * adding an epoll file descriptor inside itself.
	 */
	error = -EINVAL;
	if (f.file == tf.file || !is_file_epoll(f.file))
		goto error_tgt_fput;

	/*
	 * epoll adds to the wakeup queue at EPOLL_CTL_ADD time only,
	 * so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
	 * Also, we do not currently supported nested exclusive wakeups.
	 */
	if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
		if (op == EPOLL_CTL_MOD)
			goto error_tgt_fput;
		if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
				(epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
			goto error_tgt_fput;
	}

	/*
	 * At this point it is safe to assume that the "private_data" contains
	 * our own data structure.
	 */
	ep = f.file->private_data;

	/*
	 * When we insert an epoll file descriptor, inside another epoll file
	 * descriptor, there is the change of creating closed loops, which are
	 * better be handled here, than in more critical paths. While we are
	 * checking for loops we also determine the list of files reachable
	 * and hang them on the tfile_check_list, so we can check that we
	 * haven't created too many possible wakeup paths.
	 *
	 * We do not need to take the global 'epumutex' on EPOLL_CTL_ADD when
	 * the epoll file descriptor is attaching directly to a wakeup source,
	 * unless the epoll file descriptor is nested. The purpose of taking the
	 * 'epmutex' on add is to prevent complex toplogies such as loops and
	 * deep wakeup paths from forming in parallel through multiple
	 * EPOLL_CTL_ADD operations.
	 */
	error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
	if (error)
		goto error_tgt_fput;
	if (op == EPOLL_CTL_ADD) {
		if (!list_empty(&f.file->f_ep_links) ||
						is_file_epoll(tf.file)) {
			mutex_unlock(&ep->mtx);
			error = epoll_mutex_lock(&epmutex, 0, nonblock);
			if (error)
				goto error_tgt_fput;
			full_check = 1;
			if (is_file_epoll(tf.file)) {
				error = -ELOOP;
				if (ep_loop_check(ep, tf.file) != 0)
					goto error_tgt_fput;
			} else {
				get_file(tf.file);
				list_add(&tf.file->f_tfile_llink,
							&tfile_check_list);
			}
			error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
			if (error)
				goto error_tgt_fput;
			if (is_file_epoll(tf.file)) {
				tep = tf.file->private_data;
				error = epoll_mutex_lock(&tep->mtx, 1, nonblock);
				if (error) {
					mutex_unlock(&ep->mtx);
					goto error_tgt_fput;
				}
			}
		}
	}

	/*
	 * Try to lookup the file inside our RB tree, Since we grabbed "mtx"
	 * above, we can be sure to be able to use the item looked up by
	 * ep_find() till we release the mutex.
	 */
	epi = ep_find(ep, tf.file, fd);

	error = -EINVAL;
	switch (op) {
	case EPOLL_CTL_ADD:
		if (!epi) {
			epds->events |= EPOLLERR | EPOLLHUP;
			error = ep_insert(ep, epds, tf.file, fd, full_check);
		} else
			error = -EEXIST;
		break;
	case EPOLL_CTL_DEL:
		if (epi)
			error = ep_remove(ep, epi);
		else
			error = -ENOENT;
		break;
	case EPOLL_CTL_MOD:
		if (epi) {
			if (!(epi->event.events & EPOLLEXCLUSIVE)) {
				epds->events |= EPOLLERR | EPOLLHUP;
				error = ep_modify(ep, epi, epds);
			}
		} else
			error = -ENOENT;
		break;
	}
	if (tep != NULL)
		mutex_unlock(&tep->mtx);
	mutex_unlock(&ep->mtx);

error_tgt_fput:
	if (full_check) {
		clear_tfile_check_list();
		mutex_unlock(&epmutex);
	}

	fdput(tf);
error_fput:
	fdput(f);
error_return:

	return error;
}


static bool ep_busy_loop_end(void *p, unsigned long start_time)
{
	struct eventpoll *ep = p;

	return ep_events_available(ep) || busy_loop_timeout(start_time);
}


static void ep_remove_wait_queue(struct eppoll_entry *pwq)
{
	wait_queue_head_t *whead;

	rcu_read_lock();
	/*
	 * If it is cleared by POLLFREE, it should be rcu-safe.
	 * If we read NULL we need a barrier paired with
	 * smp_store_release() in ep_poll_callback(), otherwise
	 * we rely on whead->lock.
	 */
	whead = smp_load_acquire(&pwq->whead);
	if (whead)
		remove_wait_queue(whead, &pwq->wait);
	rcu_read_unlock();
}


void eventpoll_release_file(struct file *file)
{
	struct eventpoll *ep;
	struct epitem *epi, *next;

	/*
	 * We don't want to get "file->f_lock" because it is not
	 * necessary. It is not necessary because we're in the "struct file"
	 * cleanup path, and this means that no one is using this file anymore.
	 * So, for example, epoll_ctl() cannot hit here since if we reach this
	 * point, the file counter already went to zero and fget() would fail.
	 * The only hit might come from ep_free() but by holding the mutex
	 * will correctly serialize the operation. We do need to acquire
	 * "ep->mtx" after "epmutex" because ep_remove() requires it when called
	 * from anywhere but ep_free().
	 *
	 * Besides, ep_remove() acquires the lock, so we can't hold it here.
	 */
	mutex_lock(&epmutex);
	list_for_each_entry_safe(epi, next, &file->f_ep_links, fllink) {
		ep = epi->ep;
		mutex_lock_nested(&ep->mtx, 0);
		ep_remove(ep, epi);
		mutex_unlock(&ep->mtx);
	}
	mutex_unlock(&epmutex);
}


static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
{
	int pwake = 0;
	struct epitem *epi = ep_item_from_wait(wait);
	struct eventpoll *ep = epi->ep;
	__poll_t pollflags = key_to_poll(key);
	unsigned long flags;
	int ewake = 0;

	read_lock_irqsave(&ep->lock, flags);

	ep_set_busy_poll_napi_id(epi);

	/*
	 * If the event mask does not contain any poll(2) event, we consider the
	 * descriptor to be disabled. This condition is likely the effect of the
	 * EPOLLONESHOT bit that disables the descriptor when an event is received,
	 * until the next EPOLL_CTL_MOD will be issued.
	 */
	if (!(epi->event.events & ~EP_PRIVATE_BITS))
		goto out_unlock;

	/*
	 * Check the events coming with the callback. At this stage, not
	 * every device reports the events in the "key" parameter of the
	 * callback. We need to be able to handle both cases here, hence the
	 * test for "key" != NULL before the event match test.
	 */
	if (pollflags && !(pollflags & epi->event.events))
		goto out_unlock;

	/*
	 * If we are transferring events to userspace, we can hold no locks
	 * (because we're accessing user memory, and because of linux f_op->poll()
	 * semantics). All the events that happen during that period of time are
	 * chained in ep->ovflist and requeued later on.
	 */
	if (READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR) {
		if (chain_epi_lockless(epi))
			ep_pm_stay_awake_rcu(epi);
	} else if (!ep_is_linked(epi)) {
		/* In the usual case, add event to ready list. */
		if (list_add_tail_lockless(&epi->rdllink, &ep->rdllist))
			ep_pm_stay_awake_rcu(epi);
	}

	/*
	 * Wake up ( if active ) both the eventpoll wait list and the ->poll()
	 * wait list.
	 */
	if (waitqueue_active(&ep->wq)) {
		if ((epi->event.events & EPOLLEXCLUSIVE) &&
					!(pollflags & POLLFREE)) {
			switch (pollflags & EPOLLINOUT_BITS) {
			case EPOLLIN:
				if (epi->event.events & EPOLLIN)
					ewake = 1;
				break;
			case EPOLLOUT:
				if (epi->event.events & EPOLLOUT)
					ewake = 1;
				break;
			case 0:
				ewake = 1;
				break;
			}
		}
		wake_up(&ep->wq);
	}
	if (waitqueue_active(&ep->poll_wait))
		pwake++;

out_unlock:
	read_unlock_irqrestore(&ep->lock, flags);

	/* We have to call this outside the lock */
	if (pwake)
		ep_poll_safewake(ep, epi);

	if (!(epi->event.events & EPOLLEXCLUSIVE))
		ewake = 1;

	if (pollflags & POLLFREE) {
		/*
		 * If we race with ep_remove_wait_queue() it can miss
		 * ->whead = NULL and do another remove_wait_queue() after
		 * us, so we can't use __remove_wait_queue().
		 */
		list_del_init(&wait->entry);
		/*
		 * ->whead != NULL protects us from the race with ep_free()
		 * or ep_remove(), ep_remove_wait_queue() takes whead->lock
		 * held by the caller. Once we nullify it, nothing protects
		 * ep/epi or even wait.
		 */
		smp_store_release(&ep_pwq_from_wait(wait)->whead, NULL);
	}

	return ewake;
}


static int ep_remove(struct eventpoll *ep, struct epitem *epi)
{
	struct file *file = epi->ffd.file;

	lockdep_assert_irqs_enabled();

	/*
	 * Removes poll wait queue hooks.
	 */
	ep_unregister_pollwait(ep, epi);

	/* Remove the current item from the list of epoll hooks */
	spin_lock(&file->f_lock);
	list_del_rcu(&epi->fllink);
	spin_unlock(&file->f_lock);

	rb_erase_cached(&epi->rbn, &ep->rbr);

	write_lock_irq(&ep->lock);
	if (ep_is_linked(epi))
		list_del_init(&epi->rdllink);
	write_unlock_irq(&ep->lock);

	wakeup_source_unregister(ep_wakeup_source(epi));
	/*
	 * At this point it is safe to free the eventpoll item. Use the union
	 * field epi->rcu, since we are trying to minimize the size of
	 * 'struct epitem'. The 'rbn' field is no longer in use. Protected by
	 * ep->mtx. The rcu read side, reverse_path_check_proc(), does not make
	 * use of the rbn field.
	 */
	call_rcu(&epi->rcu, epi_rcu_free);

	atomic_long_dec(&ep->user->epoll_watches);

	return 0;
}


static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
{
	struct eventpoll *ep_src;
	unsigned long flags;
	u8 nests = 0;

	/*
	 * To set the subclass or nesting level for spin_lock_irqsave_nested()
	 * it might be natural to create a per-cpu nest count. However, since
	 * we can recurse on ep->poll_wait.lock, and a non-raw spinlock can
	 * schedule() in the -rt kernel, the per-cpu variable are no longer
	 * protected. Thus, we are introducing a per eventpoll nest field.
	 * If we are not being call from ep_poll_callback(), epi is NULL and
	 * we are at the first level of nesting, 0. Otherwise, we are being
	 * called from ep_poll_callback() and if a previous wakeup source is
	 * not an epoll file itself, we are at depth 1 since the wakeup source
	 * is depth 0. If the wakeup source is a previous epoll file in the
	 * wakeup chain then we use its nests value and record ours as
	 * nests + 1. The previous epoll file nests value is stable since its
	 * already holding its own poll_wait.lock.
	 */
	if (epi) {
		if ((is_file_epoll(epi->ffd.file))) {
			ep_src = epi->ffd.file->private_data;
			nests = ep_src->nests;
		} else {
			nests = 1;
		}
	}
	spin_lock_irqsave_nested(&ep->poll_wait.lock, flags, nests);
	ep->nests = nests + 1;
	wake_up_locked_poll(&ep->poll_wait, EPOLLIN);
	ep->nests = 0;
	spin_unlock_irqrestore(&ep->poll_wait.lock, flags);
}


static void epi_rcu_free(struct rcu_head *head)
{
	struct epitem *epi = container_of(head, struct epitem, rcu);
	kmem_cache_free(epi_cache, epi);
}


static __poll_t ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
			       void *priv)
{
	struct epitem *epi, *tmp;
	poll_table pt;
	int depth = *(int *)priv;

	init_poll_funcptr(&pt, NULL);
	depth++;

	list_for_each_entry_safe(epi, tmp, head, rdllink) {
		if (ep_item_poll(epi, &pt, depth)) {
			return EPOLLIN | EPOLLRDNORM;
		} else {
			/*
			 * Item has been dropped into the ready list by the poll
			 * callback, but it's not actually ready, as far as
			 * caller requested events goes. We can remove it here.
			 */
			__pm_relax(ep_wakeup_source(epi));
			list_del_init(&epi->rdllink);
		}
	}

	return 0;
}


static __poll_t ep_eventpoll_poll(struct file *file, poll_table *wait)
{
	struct eventpoll *ep = file->private_data;
	int depth = 0;

	/* Insert inside our poll wait queue */
	poll_wait(file, &ep->poll_wait, wait);

	/*
	 * Proceed to find out if wanted events are really available inside
	 * the ready list.
	 */
	return ep_scan_ready_list(ep, ep_read_events_proc,
				  &depth, depth, false);
}


static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
				 poll_table *pt)
{
	struct epitem *epi = ep_item_from_epqueue(pt);
	struct eppoll_entry *pwq;

	if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
		init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
		pwq->whead = whead;
		pwq->base = epi;
		if (epi->event.events & EPOLLEXCLUSIVE)
			add_wait_queue_exclusive(whead, &pwq->wait);
		else
			add_wait_queue(whead, &pwq->wait);
		list_add_tail(&pwq->llink, &epi->pwqlist);
		epi->nwait++;
	} else {
		/* We have to signal that an error occurred */
		epi->nwait = -1;
	}
}


static inline struct timespec64 ep_set_mstimeout(long ms)
{
	struct timespec64 now, ts = {
		.tv_sec = ms / MSEC_PER_SEC,
		.tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
	};

	ktime_get_ts64(&now);
	return timespec64_add_safe(now, ts);
}


static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
{
	struct eventpoll *ep;
	unsigned int napi_id;
	struct socket *sock;
	struct sock *sk;
	int err;

	if (!net_busy_loop_on())
		return;

	sock = sock_from_file(epi->ffd.file, &err);
	if (!sock)
		return;

	sk = sock->sk;
	if (!sk)
		return;

	napi_id = READ_ONCE(sk->sk_napi_id);
	ep = epi->ep;

	/* Non-NAPI IDs can be rejected
	 *	or
	 * Nothing to do if we already have this ID
	 */
	if (napi_id < MIN_NAPI_ID || napi_id == ep->napi_id)
		return;

	/* record NAPI ID for use in next busy poll */
	ep->napi_id = napi_id;
}


static inline bool chain_epi_lockless(struct epitem *epi)
{
	struct eventpoll *ep = epi->ep;

	/* Fast preliminary check */
	if (epi->next != EP_UNACTIVE_PTR)
		return false;

	/* Check that the same epi has not been just chained from another CPU */
	if (cmpxchg(&epi->next, EP_UNACTIVE_PTR, NULL) != EP_UNACTIVE_PTR)
		return false;

	/* Atomically exchange tail */
	epi->next = xchg(&ep->ovflist, epi);

	return true;
}


static int do_epoll_create(int flags)
{
	int error, fd;
	struct eventpoll *ep = NULL;
	struct file *file;

	/* Check the EPOLL_* constant for consistency.  */
	BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);

	if (flags & ~EPOLL_CLOEXEC)
		return -EINVAL;
	/*
	 * Create the internal data structure ("struct eventpoll").
	 */
	error = ep_alloc(&ep);
	if (error < 0)
		return error;
	/*
	 * Creates all the items needed to setup an eventpoll file. That is,
	 * a file structure and a free file descriptor.
	 */
	fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
	if (fd < 0) {
		error = fd;
		goto out_free_ep;
	}
	file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
				 O_RDWR | (flags & O_CLOEXEC));
	if (IS_ERR(file)) {
		error = PTR_ERR(file);
		goto out_free_fd;
	}
	ep->file = file;
	fd_install(fd, file);
	return fd;

out_free_fd:
	put_unused_fd(fd);
out_free_ep:
	ep_free(ep);
	return error;
}


static inline void ep_reset_busy_poll_napi_id(struct eventpoll *ep)
{
	if (ep->napi_id)
		ep->napi_id = 0;
}


static inline struct wakeup_source *ep_wakeup_source(struct epitem *epi)
{
	return rcu_dereference_check(epi->ws, lockdep_is_held(&epi->ep->mtx));
}


SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
		struct epoll_event __user *, event)
{
	struct epoll_event epds;

	if (ep_op_has_event(op) &&
	    copy_from_user(&epds, event, sizeof(struct epoll_event)))
		return -EFAULT;

	return do_epoll_ctl(epfd, op, fd, &epds, false);
}


static inline void ep_reset_busy_poll_napi_id(struct eventpoll *ep)
{
}


yin parser BUGFIX invalid memory access

... in case there were some unresolved
extensions.
Fixes #1454
Fixes #1455

read_yin_case(struct lys_module *module, struct lys_node *parent, struct lyxml_elem *yin, int options,
              struct unres_schema *unres)
{
    struct ly_ctx *ctx = module->ctx;
    struct lyxml_elem *sub, *next, root;
    struct lys_node_case *cs;
    struct lys_node *retval, *node = NULL;
    int c_ftrs = 0, c_ext = 0, ret;
    void *reallocated;

    /* init */
    memset(&root, 0, sizeof root);

    cs = calloc(1, sizeof *cs);
    LY_CHECK_ERR_RETURN(!cs, LOGMEM(ctx), NULL);
    cs->nodetype = LYS_CASE;
    cs->prev = (struct lys_node *)cs;
    retval = (struct lys_node *)cs;

    if (read_yin_common(module, parent, retval, LYEXT_PAR_NODE, yin,
            OPT_IDENT | OPT_MODULE | (!(options & LYS_PARSE_OPT_CFG_MASK) ? OPT_CFG_INHERIT : 0), unres)) {
        goto error;
    }

    LOGDBG(LY_LDGYIN, "parsing %s statement \"%s\"", yin->name, retval->name);

    /* insert the node into the schema tree */
    if (lys_node_addchild(parent, lys_main_module(module), retval, options)) {
        goto error;
    }

    /* process choice's specific children */
    LY_TREE_FOR_SAFE(yin->child, next, sub) {
        if (strcmp(sub->ns->value, LY_NSYIN)) {
            /* extension */
            YIN_CHECK_ARRAY_OVERFLOW_GOTO(ctx, c_ext, retval->ext_size, "extensions", "case", error);
            c_ext++;
        } else if (!strcmp(sub->name, "container") ||
                !strcmp(sub->name, "leaf-list") ||
                !strcmp(sub->name, "leaf") ||
                !strcmp(sub->name, "list") ||
                !strcmp(sub->name, "uses") ||
                !strcmp(sub->name, "choice") ||
                !strcmp(sub->name, "anyxml") ||
                !strcmp(sub->name, "anydata")) {

            lyxml_unlink_elem(ctx, sub, 2);
            lyxml_add_child(ctx, &root, sub);
        } else if (!strcmp(sub->name, "if-feature")) {
            YIN_CHECK_ARRAY_OVERFLOW_GOTO(ctx, c_ftrs, retval->iffeature_size, "if-features", "case", error);
            c_ftrs++;
        } else if (!strcmp(sub->name, "when")) {
            if (cs->when) {
                LOGVAL(ctx, LYE_TOOMANY, LY_VLOG_LYS, retval, sub->name, yin->name);
                goto error;
            }

            cs->when = read_yin_when(module, sub, unres);
            if (!cs->when) {
                goto error;
            }

            lyxml_free(ctx, sub);
        } else {
            LOGVAL(ctx, LYE_INSTMT, LY_VLOG_LYS, retval, sub->name);
            goto error;
        }
    }

    if (c_ftrs) {
        cs->iffeature = calloc(c_ftrs, sizeof *cs->iffeature);
        LY_CHECK_ERR_GOTO(!cs->iffeature, LOGMEM(ctx), error);
    }
    if (c_ext) {
        /* some extensions may be already present from the substatements */
        reallocated = realloc(retval->ext, (c_ext + retval->ext_size) * sizeof *retval->ext);
        LY_CHECK_ERR_GOTO(!reallocated, LOGMEM(ctx), error);
        retval->ext = reallocated;

        /* init memory */
        memset(&retval->ext[retval->ext_size], 0, c_ext * sizeof *retval->ext);
    }

    LY_TREE_FOR_SAFE(yin->child, next, sub) {
        if (strcmp(sub->ns->value, LY_NSYIN)) {
            /* extension */
            ret = lyp_yin_fill_ext(retval, LYEXT_PAR_NODE, 0, 0, module, sub, &retval->ext, &retval->ext_size, unres);
            if (ret) {
                goto error;
            }
        } else {
            /* if-feature */
            ret = fill_yin_iffeature(retval, 0, sub, &cs->iffeature[cs->iffeature_size], unres);
            cs->iffeature_size++;
            if (ret) {
                goto error;
            }
        }
    }

    lyp_reduce_ext_list(&retval->ext, retval->ext_size, c_ext + retval->ext_size);

    /* last part - process data nodes */
    LY_TREE_FOR_SAFE(root.child, next, sub) {
        if (!strcmp(sub->name, "container")) {
            node = read_yin_container(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "leaf-list")) {
            node = read_yin_leaflist(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "leaf")) {
            node = read_yin_leaf(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "list")) {
            node = read_yin_list(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "choice")) {
            node = read_yin_choice(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "uses")) {
            node = read_yin_uses(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "anyxml")) {
            node = read_yin_anydata(module, retval, sub, LYS_ANYXML, options, unres);
        } else if (!strcmp(sub->name, "anydata")) {
            node = read_yin_anydata(module, retval, sub, LYS_ANYDATA, options, unres);
        }
        if (!node) {
            goto error;
        }

        lyxml_free(ctx, sub);
    }

    /* check XPath dependencies */
    if (!(ctx->models.flags & LY_CTX_TRUSTED) && cs->when) {
        if (options & LYS_PARSE_OPT_INGRP) {
            if (lyxp_node_check_syntax(retval)) {
                goto error;
            }
        } else {
            if (unres_schema_add_node(module, unres, retval, UNRES_XPATH, NULL) == -1) {
                goto error;
            }
        }
    }

    return retval;

error:
    while (root.child) {
        lyxml_free(ctx, root.child);
    }
    lys_node_free(ctx, retval, NULL, 0);

    return NULL;
}

In function read_yin_container() in libyang <= v1.0.225, it doesn't check whether the value of retval->ext[r] is NULL. In some cases, it can be NULL, which leads to the operation of retval->ext[r]->flags that results in a crash.


yin_read_submodule(struct lys_module *module, const char *data, struct unres_schema *unres)
{
    struct ly_ctx *ctx = module->ctx;
    struct lyxml_elem *yin;
    struct lys_submodule *submodule = NULL;
    const char *value;

    yin = lyxml_parse_mem(ctx, data, LYXML_PARSE_NOMIXEDCONTENT);
    if (!yin) {
        return NULL;
    }

    /* check root element */
    if (!yin->name || strcmp(yin->name, "submodule")) {
        LOGVAL(ctx, LYE_INSTMT, LY_VLOG_NONE, NULL, yin->name);
        goto error;
    }

    GETVAL(ctx, value, yin, "name");
    if (lyp_check_identifier(ctx, value, LY_IDENT_NAME, NULL, NULL)) {
        goto error;
    }

    submodule = calloc(1, sizeof *submodule);
    LY_CHECK_ERR_GOTO(!submodule, LOGMEM(ctx), error);

    submodule->ctx = ctx;
    submodule->name = lydict_insert(ctx, value, strlen(value));
    submodule->type = 1;
    submodule->implemented = module->implemented;
    submodule->belongsto = module;

    /* add into the list of processed modules */
    if (lyp_check_circmod_add((struct lys_module *)submodule)) {
        goto error;
    }

    LOGVRB("Reading submodule \"%s\".", submodule->name);
    /* module cannot be changed in this case and 1 cannot be returned */
    if (read_sub_module(module, submodule, yin, unres)) {
        goto error;
    }

    lyp_sort_revisions((struct lys_module *)submodule);

    /* cleanup */
    lyxml_free(ctx, yin);
    lyp_check_circmod_pop(ctx);

    LOGVRB("Submodule \"%s\" successfully parsed.", submodule->name);
    return submodule;

error:
    /* cleanup */
    lyxml_free(ctx, yin);
    if (!submodule) {
        LOGERR(ctx, ly_errno, "Submodule parsing failed.");
        return NULL;
    }

    LOGERR(ctx, ly_errno, "Submodule \"%s\" parsing failed.", submodule->name);

    unres_schema_free((struct lys_module *)submodule, &unres, 0);
    lyp_check_circmod_pop(ctx);
    lys_sub_module_remove_devs_augs((struct lys_module *)submodule);
    lys_submodule_module_data_free(submodule);
    lys_submodule_free(submodule, NULL);
    return NULL;
}


fill_yin_revision(struct lys_module *module, struct lyxml_elem *yin, struct lys_revision *rev,
                  struct unres_schema *unres)
{
    struct ly_ctx *ctx = module->ctx;
    struct lyxml_elem *next, *child;
    const char *value;

    GETVAL(ctx, value, yin, "date");
    if (lyp_check_date(ctx, value)) {
        goto error;
    }
    memcpy(rev->date, value, LY_REV_SIZE - 1);

    LY_TREE_FOR_SAFE(yin->child, next, child) {
        if (!child->ns) {
            /* garbage */
            continue;
        } else if (strcmp(child->ns->value, LY_NSYIN)) {
            /* possible extension instance */
            if (lyp_yin_parse_subnode_ext(module, rev, LYEXT_PAR_REVISION,
                                          child, LYEXT_SUBSTMT_SELF, 0, unres)) {
                goto error;
            }
        } else if (!strcmp(child->name, "description")) {
            if (rev->dsc) {
                LOGVAL(ctx, LYE_TOOMANY, LY_VLOG_NONE, NULL, child->name, yin->name);
                goto error;
            }
            if (lyp_yin_parse_subnode_ext(module, rev, LYEXT_PAR_REVISION,
                                          child, LYEXT_SUBSTMT_DESCRIPTION, 0, unres)) {
                goto error;
            }
            rev->dsc = read_yin_subnode(ctx, child, "text");
            if (!rev->dsc) {
                goto error;
            }
        } else if (!strcmp(child->name, "reference")) {
            if (rev->ref) {
                LOGVAL(ctx, LYE_TOOMANY, LY_VLOG_NONE, NULL, child->name, yin->name);
                goto error;
            }
            if (lyp_yin_parse_subnode_ext(module, rev, LYEXT_PAR_REVISION,
                                          child, LYEXT_SUBSTMT_REFERENCE, 0, unres)) {
                goto error;
            }
            rev->ref = read_yin_subnode(ctx, child, "text");
            if (!rev->ref) {
                goto error;
            }
        } else {
            LOGVAL(ctx, LYE_INSTMT, LY_VLOG_NONE, NULL, child->name);
            goto error;
        }
    }

    return EXIT_SUCCESS;

error:
    return EXIT_FAILURE;
}


lyp_yin_parse_subnode_ext(struct lys_module *mod, void *elem, LYEXT_PAR elem_type,
                     struct lyxml_elem *yin, LYEXT_SUBSTMT type, uint8_t i, struct unres_schema *unres)
{
    void *reallocated;
    struct lyxml_elem *next, *child;
    int r;
    struct lys_ext_instance ***ext;
    uint8_t *ext_size;
    const char *statement;

    r = lyp_get_ext_list(mod->ctx, elem, elem_type, &ext, &ext_size, &statement);
    LY_CHECK_RETURN(r, EXIT_FAILURE);

    if (type == LYEXT_SUBSTMT_SELF) {
        /* parse for the statement self, not for the substatement */
        child = yin;
        next = NULL;
        goto parseext;
    }

    LY_TREE_FOR_SAFE(yin->child, next, child) {
        if (!child->ns) {
            LOGVAL(mod->ctx, LYE_SPEC, LY_VLOG_NONE, NULL, "Extension instance \"%s\" is missing namespace.", child->name);
            return EXIT_FAILURE;
        }
        if (!strcmp(child->ns->value, LY_NSYIN)) {
            /* skip the regular YIN nodes */
            continue;
        }

        /* parse it as extension */
parseext:

        YIN_CHECK_ARRAY_OVERFLOW_RETURN(mod->ctx, *ext_size, *ext_size, "extension", statement, EXIT_FAILURE);
        /* first, allocate a space for the extension instance in the parent elem */
        reallocated = realloc(*ext, (1 + (*ext_size)) * sizeof **ext);
        LY_CHECK_ERR_RETURN(!reallocated, LOGMEM(mod->ctx), EXIT_FAILURE);
        (*ext) = reallocated;

        /* init memory */
        (*ext)[(*ext_size)] = NULL;

        /* parse YIN data */
        r = lyp_yin_fill_ext(elem, elem_type, type, i, mod, child, ext, ext_size, unres);
        if (r) {
            return EXIT_FAILURE;
        }

        lyp_reduce_ext_list(ext, *ext_size, 1 + (*ext_size));

        /* done - do not free the child, it is unlinked in lyp_yin_fill_ext */
    }

    return EXIT_SUCCESS;
}


lyp_yin_fill_ext(void *parent, LYEXT_PAR parent_type, LYEXT_SUBSTMT substmt, uint8_t substmt_index,
             struct lys_module *module, struct lyxml_elem *yin, struct lys_ext_instance ***ext,
             uint8_t *ext_size, struct unres_schema *unres)
{
    struct unres_ext *info;
    int rc;

    info = malloc(sizeof *info);
    LY_CHECK_ERR_RETURN(!info, LOGMEM(module->ctx), EXIT_FAILURE);
    lyxml_unlink(module->ctx, yin);
    info->data.yin = yin;
    info->datatype = LYS_IN_YIN;
    info->parent = parent;
    info->mod = module;
    info->parent_type = parent_type;
    info->substmt = substmt;
    info->substmt_index = substmt_index;
    info->ext_index = *ext_size;

    rc = unres_schema_add_node(module, unres, ext, UNRES_EXT, (struct lys_node *)info);
    if (!rc && !(*ext)[*ext_size]) {
        /* extension instance is skipped */
    } else {
        ++(*ext_size);
    }

    return rc == -1 ? EXIT_FAILURE : EXIT_SUCCESS;
}


read_yin_subnode(struct ly_ctx *ctx, struct lyxml_elem *node, const char *name)
{
    int len;

    /* there should be <text> child */
    if (!node->child || !node->child->name || strcmp(node->child->name, name)) {
        LOGERR(ctx, LY_EVALID, "Expected \"%s\" element in \"%s\" element.", name, node->name);
        LOGVAL(ctx, LYE_INARG, LY_VLOG_NONE, NULL, name, node->name);
        return NULL;
    } else if (node->child->content) {
        len = strlen(node->child->content);
        return lydict_insert(ctx, node->child->content, len);
    } else {
        return lydict_insert(ctx, "", 0);
    }
}


yin_parse_extcomplex_flag(struct lys_module *mod, struct lyxml_elem *node,
                          struct lys_ext_instance_complex *ext, LY_STMT stmt,
                          const char *val1_str, const char *val2_str, uint16_t mask,
                          uint16_t val1, uint16_t val2, struct unres_schema *unres)
{
    uint16_t *val;
    const char *str;

    val = yin_getplace_for_extcomplex_flags(node, ext, stmt, mask);
    if (!val) {
        return EXIT_FAILURE;
    }

    str = lyxml_get_attr(node, "value", NULL);
    if (!str) {
        LOGVAL(mod->ctx, LYE_MISSARG, LY_VLOG_NONE, NULL, "value", node->name);
    } else if (!strcmp(val1_str, str)) {
        *val = *val | val1;
    } else if (!strcmp(val2_str, str)) {
        *val = *val | val2;
    } else {
        /* unknown value */
        LOGVAL(mod->ctx, LYE_INARG, LY_VLOG_NONE, NULL, str, node->name);
        return EXIT_FAILURE;
    }
    if (lyp_yin_parse_subnode_ext(mod, ext, LYEXT_PAR_EXTINST, node, (LYEXT_SUBSTMT)stmt, 0, unres)) {
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}


yin_getplace_for_extcomplex_struct(struct lyxml_elem *node, struct lys_ext_instance_complex *ext, LY_STMT stmt)
{
    int c;
    void **data, ***p = NULL;
    void *reallocated;
    struct lyext_substmt *info;

    data = lys_ext_complex_get_substmt(stmt, ext, &info);
    if (!data) {
        LOGVAL(ext->module->ctx, LYE_INCHILDSTMT, LY_VLOG_NONE, NULL, node->name, node->parent->name);
        return NULL;
    }
    if (info->cardinality < LY_STMT_CARD_SOME && *data) {
        LOGVAL(ext->module->ctx, LYE_TOOMANY, LY_VLOG_NONE, NULL, node->name, node->parent->name);
        return NULL;
    }

    c = 0;
    if (info->cardinality >= LY_STMT_CARD_SOME) {
        /* there can be multiple instances, so instead of pointer to array,
         * we have in data pointer to pointer to array */
        p = (void ***)data;
        data = *p;
        if (!data) {
            /* allocate initial array */
            *p = data = malloc(2 * sizeof(void *));
            LY_CHECK_ERR_RETURN(!data, LOGMEM(ext->module->ctx), NULL);
        } else {
            for (c = 0; *data; data++, c++);
        }
    }

    if (p) {
        /* enlarge the array */
        reallocated = realloc(*p, (c + 2) * sizeof(void *));
        LY_CHECK_ERR_RETURN(!reallocated, LOGMEM(ext->module->ctx), NULL);
        *p = reallocated;
        data = *p;
        data[c + 1] = NULL;
    }

    return &data[c];
}


yin_parse_extcomplex_bool(struct lys_module *mod, struct lyxml_elem *node,
                          struct lys_ext_instance_complex *ext, LY_STMT stmt,
                          const char *true_val, const char *false_val, struct unres_schema *unres)
{
    uint8_t *val;
    const char *str;
    struct lyext_substmt *info;

    val = lys_ext_complex_get_substmt(stmt, ext, &info);
    if (!val) {
        LOGVAL(mod->ctx, LYE_INCHILDSTMT, LY_VLOG_NONE, NULL, node->name, node->parent->name);
        return EXIT_FAILURE;
    }
    if (*val) {
        LOGVAL(mod->ctx, LYE_TOOMANY, LY_VLOG_NONE, NULL, node->name, node->parent->name);
        return EXIT_FAILURE;
    }

    if (lyp_yin_parse_subnode_ext(mod, ext, LYEXT_PAR_EXTINST, node, (LYEXT_SUBSTMT)stmt, 0, unres)) {
        return EXIT_FAILURE;
    }

    str = lyxml_get_attr(node, "value", NULL);
    if (!str) {
        LOGVAL(mod->ctx, LYE_MISSARG, LY_VLOG_NONE, NULL, "value", node->name);
    } else if (true_val && !strcmp(true_val, str)) {
        /* true value */
        *val = 1;
    } else if (false_val && !strcmp(false_val, str)) {
        /* false value */
        *val = 2;
    } else {
        /* unknown value */
        LOGVAL(mod->ctx, LYE_INARG, LY_VLOG_NONE, NULL, str, node->name);
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}


fill_yin_must(struct lys_module *module, struct lyxml_elem *yin, struct lys_restr *must, struct unres_schema *unres)
{
    int ret = EXIT_FAILURE;
    const char *value;

    must->expr = NULL;
    GETVAL(module->ctx, value, yin, "condition");
    must->expr = transform_schema2json(module, value);
    if (!must->expr) {
        goto error;
    }

    ret = read_restr_substmt(module, must, yin, unres);

error:
    if (ret) {
        lydict_remove(module->ctx, must->expr);
        must->expr = NULL;
    }
    return ret;
}


read_yin_rpc_action(struct lys_module *module, struct lys_node *parent, struct lyxml_elem *yin,
                    int options, struct unres_schema *unres)
{
    struct ly_ctx *ctx = module->ctx;
    struct lyxml_elem *sub, *next, root;
    struct lys_node *node = NULL;
    struct lys_node *retval;
    struct lys_node_rpc_action *rpc;
    int r;
    int c_tpdf = 0, c_ftrs = 0, c_input = 0, c_output = 0, c_ext = 0;
    void *reallocated;

    if (!strcmp(yin->name, "action") && (module->version < 2)) {
        LOGVAL(ctx, LYE_INSTMT, LY_VLOG_LYS, parent, "action");
        return NULL;
    }

    /* init */
    memset(&root, 0, sizeof root);

    rpc = calloc(1, sizeof *rpc);
    LY_CHECK_ERR_RETURN(!rpc, LOGMEM(ctx), NULL);

    rpc->nodetype = (!strcmp(yin->name, "rpc") ? LYS_RPC : LYS_ACTION);
    rpc->prev = (struct lys_node *)rpc;
    retval = (struct lys_node *)rpc;

    if (read_yin_common(module, parent, retval, LYEXT_PAR_NODE, yin, OPT_IDENT | OPT_MODULE, unres)) {
        goto error;
    }

    LOGDBG(LY_LDGYIN, "parsing %s statement \"%s\"", yin->name, retval->name);

    /* insert the node into the schema tree */
    if (lys_node_addchild(parent, lys_main_module(module), retval, options)) {
        goto error;
    }

    /* process rpc's specific children */
    LY_TREE_FOR_SAFE(yin->child, next, sub) {
        if (strcmp(sub->ns->value, LY_NSYIN)) {
            /* extension */
            YIN_CHECK_ARRAY_OVERFLOW_GOTO(ctx, c_ext, retval->ext_size, "extensions",
                                          rpc->nodetype == LYS_RPC ? "rpc" : "action", error);
            c_ext++;
            continue;
        } else if (!strcmp(sub->name, "input")) {
            if (c_input) {
                LOGVAL(ctx, LYE_TOOMANY, LY_VLOG_LYS, retval, sub->name, yin->name);
                goto error;
            }
            c_input++;
            lyxml_unlink_elem(ctx, sub, 2);
            lyxml_add_child(ctx, &root, sub);
        } else if (!strcmp(sub->name, "output")) {
            if (c_output) {
                LOGVAL(ctx, LYE_TOOMANY, LY_VLOG_LYS, retval, sub->name, yin->name);
                goto error;
            }
            c_output++;
            lyxml_unlink_elem(ctx, sub, 2);
            lyxml_add_child(ctx, &root, sub);

            /* data statements */
        } else if (!strcmp(sub->name, "grouping")) {
            lyxml_unlink_elem(ctx, sub, 2);
            lyxml_add_child(ctx, &root, sub);

            /* array counters */
        } else if (!strcmp(sub->name, "typedef")) {
            YIN_CHECK_ARRAY_OVERFLOW_GOTO(ctx, c_tpdf, rpc->tpdf_size, "typedefs",
                                          rpc->nodetype == LYS_RPC ? "rpc" : "action", error);
            c_tpdf++;
        } else if (!strcmp(sub->name, "if-feature")) {
            YIN_CHECK_ARRAY_OVERFLOW_GOTO(ctx, c_ftrs, retval->iffeature_size, "if-features",
                                          rpc->nodetype == LYS_RPC ? "rpc" : "action", error);
            c_ftrs++;
        } else {
            LOGVAL(ctx, LYE_INSTMT, LY_VLOG_LYS, retval, sub->name);
            goto error;
        }
    }

    /* middle part - process nodes with cardinality of 0..n except the data nodes */
    if (c_tpdf) {
        rpc->tpdf = calloc(c_tpdf, sizeof *rpc->tpdf);
        LY_CHECK_ERR_GOTO(!rpc->tpdf, LOGMEM(ctx), error);
    }
    if (c_ftrs) {
        rpc->iffeature = calloc(c_ftrs, sizeof *rpc->iffeature);
        LY_CHECK_ERR_GOTO(!rpc->iffeature, LOGMEM(ctx), error);
    }
    if (c_ext) {
        /* some extensions may be already present from the substatements */
        reallocated = realloc(retval->ext, (c_ext + retval->ext_size) * sizeof *retval->ext);
        LY_CHECK_ERR_GOTO(!reallocated, LOGMEM(ctx), error);
        retval->ext = reallocated;

        /* init memory */
        memset(&retval->ext[retval->ext_size], 0, c_ext * sizeof *retval->ext);
    }

    LY_TREE_FOR_SAFE(yin->child, next, sub) {
        if (strcmp(sub->ns->value, LY_NSYIN)) {
            /* extension */
            r = lyp_yin_fill_ext(retval, LYEXT_PAR_NODE, 0, 0, module, sub, &retval->ext, &retval->ext_size, unres);
            if (r) {
                goto error;
            }
        } else if (!strcmp(sub->name, "typedef")) {
            r = fill_yin_typedef(module, retval, sub, &rpc->tpdf[rpc->tpdf_size], unres);
            rpc->tpdf_size++;
            if (r) {
                goto error;
            }
        } else if (!strcmp(sub->name, "if-feature")) {
            r = fill_yin_iffeature(retval, 0, sub, &rpc->iffeature[rpc->iffeature_size], unres);
            rpc->iffeature_size++;
            if (r) {
                goto error;
            }
        }
    }

    lyp_reduce_ext_list(&retval->ext, retval->ext_size, c_ext + retval->ext_size);

    /* last part - process data nodes */
    LY_TREE_FOR_SAFE(root.child, next, sub) {
        if (!strcmp(sub->name, "grouping")) {
            node = read_yin_grouping(module, retval, sub, options, unres);
        } else if (!strcmp(sub->name, "input") || !strcmp(sub->name, "output")) {
            node = read_yin_input_output(module, retval, sub, options, unres);
        }
        if (!node) {
            goto error;
        }

        lyxml_free(ctx, sub);
    }

    return retval;

error:
    lys_node_free(ctx, retval, NULL, 0);
    while (root.child) {
        lyxml_free(ctx, root.child);
    }
    return NULL;
}