[FFmpeg-cvslog] avcodec/msmpeg4dec: Skip frame if its smaller than 1/8 of the minimal size
Michael Niedermayer
git at videolan.org
Mon Jan 21 13:19:42 EET 2019
ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Thu Nov 29 02:32:10 2018 +0100| [eee0cf487aade926af27d7ffb079201ef5e8287e] | committer: Michael Niedermayer
avcodec/msmpeg4dec: Skip frame if its smaller than 1/8 of the minimal size
Frames that small are not valid and of limited use for error concealment, while
being very computationally intensive to process.
Fixes: Timeout
Fixes: 11318/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSMPEG4V1_fuzzer-5710884555456512
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 09ec182864d41c990bc18f620eabb77444aeff57)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=eee0cf487aade926af27d7ffb079201ef5e8287e
---
libavcodec/msmpeg4dec.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/libavcodec/msmpeg4dec.c b/libavcodec/msmpeg4dec.c
index 457a37e745..16b67192b5 100644
--- a/libavcodec/msmpeg4dec.c
+++ b/libavcodec/msmpeg4dec.c
@@ -412,6 +412,14 @@ int ff_msmpeg4_decode_picture_header(MpegEncContext * s)
{
int code;
+ // at minimum one bit per macroblock is required at least in a valid frame,
+ // we discard frames much smaller than this. Frames smaller than 1/8 of the
+ // smallest "black/skip" frame generally contain not much recoverable content
+ // while at the same time they have the highest computational requirements
+ // per byte
+ if (get_bits_left(&s->gb) * 8LL < (s->width+15)/16 * ((s->height+15)/16))
+ return AVERROR_INVALIDDATA;
+
if(s->msmpeg4_version==1){
int start_code = get_bits_long(&s->gb, 32);
if(start_code!=0x00000100){
More information about the ffmpeg-cvslog
mailing list