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-rw-r--r--ext/exif/exif.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/ext/exif/exif.c b/ext/exif/exif.c
index 2fe54f7b3..c531d8dfa 100644
--- a/ext/exif/exif.c
+++ b/ext/exif/exif.c
@@ -2852,7 +2852,12 @@ static int exif_process_IFD_TAG(image_info_type *ImageInfo, char *dir_entry, cha
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;
- if (byte_count > IFDlength || offset_val > IFDlength-byte_count || value_ptr < dir_entry) {
+ /*
+ 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)) {
/* 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. */