ffmpeg | branch: master | Michael Niedermayer <mich...@niedermayer.cc> | Thu Jun 14 22:16:52 2018 +0200| [8d21ab4d128ddae03fe6b21542c29dee240151db] | committer: Michael Niedermayer
avcodec/lagarith: Check that the range coded data stream is consistent when the probabilities indicate no data could have been coded. Fixes: Timeout Fixes: 8638/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LAGARITH_fuzzer-5132046098759680 Fixes: 8943/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LAGARITH_fuzzer-4883030219948032 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8d21ab4d128ddae03fe6b21542c29dee240151db --- libavcodec/lagarith.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c index 0f4aa89486..ba2da2eeb2 100644 --- a/libavcodec/lagarith.c +++ b/libavcodec/lagarith.c @@ -141,6 +141,7 @@ static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb) unsigned prob, cumulative_target; unsigned cumul_prob = 0; unsigned scaled_cumul_prob = 0; + int nnz = 0; rac->prob[0] = 0; rac->prob[257] = UINT_MAX; @@ -164,6 +165,8 @@ static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb) prob = 256 - i; for (j = 0; j < prob; j++) rac->prob[++i] = 0; + }else { + nnz++; } } @@ -172,6 +175,10 @@ static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb) return -1; } + if (nnz == 1 && (show_bits_long(gb, 32) & 0xFFFFFF)) { + return AVERROR_INVALIDDATA; + } + /* Scale probabilities so cumulative probability is an even power of 2. */ scale_factor = av_log2(cumul_prob); _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog
