[FFmpeg-cvslog] avcodec/shorten: Fix bitstream end check in read_header()

Michael Niedermayer git at videolan.org
Tue Nov 20 18:39:48 EET 2018


ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sat Sep 15 02:08:20 2018 +0200| [f2640f76489464f4a0016c729aa04d46d3638abb] | committer: Michael Niedermayer

avcodec/shorten: Fix bitstream end check in read_header()

Fixes: Timeout
Fixes: 9961/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SHORTEN_fuzzer-5687856176562176

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 28b80c2d52d82eb4f73af5f818dab60946bcf299)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f2640f76489464f4a0016c729aa04d46d3638abb
---

 libavcodec/shorten.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/shorten.c b/libavcodec/shorten.c
index de2be90e77..6ec1632aac 100644
--- a/libavcodec/shorten.c
+++ b/libavcodec/shorten.c
@@ -380,7 +380,7 @@ static int read_header(ShortenContext *s)
         }
 
         skip_bytes = get_uint(s, NSKIPSIZE);
-        if ((unsigned)skip_bytes > get_bits_left(&s->gb)/8) {
+        if ((unsigned)skip_bytes > FFMAX(get_bits_left(&s->gb), 0)/8) {
             av_log(s->avctx, AV_LOG_ERROR, "invalid skip_bytes: %d\n", skip_bytes);
             return AVERROR_INVALIDDATA;
         }



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