avcodec/shorten: Fix bitstream end check in read_header()
authorMichael Niedermayer <michael@niedermayer.cc>
Sat, 15 Sep 2018 00:08:20 +0000 (02:08 +0200)
committerMichael Niedermayer <michael@niedermayer.cc>
Sun, 18 Nov 2018 01:35:03 +0000 (02:35 +0100)
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@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 28b80c2d52d82eb4f73af5f818dab60946bcf299)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
libavcodec/shorten.c

index c1a6df3..9d591bd 100644 (file)
@@ -447,7 +447,7 @@ 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;
         }