[FFmpeg-cvslog] avformat/mvdec: Check stream numbers

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Feb 23 09:27:27 2020 +0100| [618a9bea65112a27a106e02ada3ae475cc8ac1ac] | committer: Michael Niedermayer

avformat/mvdec: Check stream numbers

Fixes: null pointer dereference
Fixes: 20768/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5638648978735104.fuzz

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=618a9bea65112a27a106e02ada3ae475cc8ac1ac
---

 libavformat/mvdec.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libavformat/mvdec.c b/libavformat/mvdec.c
index f9f7e38137..64166a84b1 100644
--- a/libavformat/mvdec.c
+++ b/libavformat/mvdec.c
@@ -363,6 +363,12 @@ static int mv_read_header(AVFormatContext *avctx)
         if ((ret = read_table(avctx, NULL, parse_global_var)) < 0)
             return ret;
 
+        if (mv->nb_audio_tracks < 0  || mv->nb_video_tracks < 0 ||
+           (mv->nb_audio_tracks == 0 && mv->nb_video_tracks == 0)) {
+            av_log(avctx, AV_LOG_ERROR, "Stream count is invalid.\n");
+            return AVERROR_INVALIDDATA;
+        }
+
         if (mv->nb_audio_tracks > 1) {
             avpriv_request_sample(avctx, "Multiple audio streams support");
             return AVERROR_PATCHWELCOME;