From f80ad18afae2230c2c1802c7d829100af646874e Mon Sep 17 00:00:00 2001 From: Stanislav Malyshev Date: Mon, 29 Apr 2019 23:38:12 -0700 Subject: [PATCH] Fix bug #77950 - Heap-buffer-overflow in _estrndup via exif_process_IFD_TAG I do not completely understand what is going on there, but I am pretty sure dir_entry <= offset_base if not a normal situation, so we better not to rely on such dir_entry. --- ext/exif/exif.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/ext/exif/exif.c b/ext/exif/exif.c index a763f6c..d174def 100644 --- a/ext/exif/exif.c +++ b/ext/exif/exif.c @@ -2891,7 +2891,7 @@ static int exif_process_IFD_TAG(image_info_type *ImageInfo, char *dir_entry, cha 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)) { + 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. */