[FFmpeg-cvslog] h264: prevent theoretical infinite loop in SEI parsing
Vittorio Giovara
git at videolan.org
Sat Aug 9 19:49:32 CEST 2014
ffmpeg | branch: release/0.10 | Vittorio Giovara <vittorio.giovara at gmail.com> | Wed Jul 30 19:33:36 2014 +0100| [7585a6254bbb38148e4467793fc34211b79d5f7d] | committer: Vittorio Giovara
h264: prevent theoretical infinite loop in SEI parsing
Properly address CVE-2011-3946 and parse bitstream as described in the spec.
CC: libav-stable at libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7585a6254bbb38148e4467793fc34211b79d5f7d
---
libavcodec/h264_sei.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/libavcodec/h264_sei.c b/libavcodec/h264_sei.c
index 5995a8e..776ce57 100644
--- a/libavcodec/h264_sei.c
+++ b/libavcodec/h264_sei.c
@@ -165,17 +165,22 @@ int ff_h264_decode_sei(H264Context *h){
MpegEncContext * const s = &h->s;
while (get_bits_left(&s->gb) > 16) {
- int size, type;
+ int type = 0;
+ int size = 0;
+ int last = 0;
- type=0;
- do{
- type+= show_bits(&s->gb, 8);
- }while(get_bits(&s->gb, 8) == 255);
+ while (get_bits_left(&s->gb) >= 8 &&
+ (last = get_bits(&s->gb, 8)) == 255) {
+ type += 255;
+ }
+ type += last;
- size=0;
- do{
- size+= show_bits(&s->gb, 8);
- }while(get_bits(&s->gb, 8) == 255);
+ last = 0;
+ while (get_bits_left(&s->gb) >= 8 &&
+ (last = get_bits(&s->gb, 8)) == 255) {
+ size += 255;
+ }
+ size += last;
if (size > get_bits_left(&s->gb) / 8) {
av_log(s->avctx, AV_LOG_ERROR, "SEI type %d truncated at %d\n",
More information about the ffmpeg-cvslog
mailing list