[FFmpeg-cvslog] avcodec/h263dec: Sanity check against minimal I/P frame size

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Mon Aug 15 00:02:37 2022 +0200| [457941c11ad8b2490d71837d5e17a4d3b4ec77fe] | committer: Michael Niedermayer

avcodec/h263dec: Sanity check against minimal I/P frame size

Fixes: Timeout
Fixes: 49718/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-4874987894341632

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit ca4ff9c21cb77e024fa4ff5889826a8bee4d0e0a)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=457941c11ad8b2490d71837d5e17a4d3b4ec77fe
---

 libavcodec/h263dec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 8ee844e298..2b64cb5b3b 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -544,6 +544,8 @@ retry:
     avctx->has_b_frames = !s->low_delay;
 
     if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
+        if (s->pict_type != AV_PICTURE_TYPE_B && s->mb_num/2 > get_bits_left(&s->gb))
+            return AVERROR_INVALIDDATA;
         if (ff_mpeg4_workaround_bugs(avctx) == 1)
             goto retry;
         if (s->studio_profile != (s->idsp.idct == NULL))