[FFmpeg-cvslog] avformat/mvdec: Fix integer overflow with billions of channels

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jun 23 01:01:53 2020 +0200| [98ff949451059e2ae6a1179d85eec136f26a8c68] | committer: Michael Niedermayer

avformat/mvdec: Fix integer overflow with billions of channels

Fixes: signed integer overflow: 1394614304 * 2 cannot be represented in type 'int'
Fixes: 23491/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5697377020411904

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 b6fbbe08c325415cc784df296058beb6604f0b9c)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=98ff949451059e2ae6a1179d85eec136f26a8c68
---

 libavformat/mvdec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/mvdec.c b/libavformat/mvdec.c
index a746eb4b08..e62e6aa584 100644
--- a/libavformat/mvdec.c
+++ b/libavformat/mvdec.c
@@ -266,7 +266,7 @@ static void read_index(AVIOContext *pb, AVStream *st)
         avio_skip(pb, 8);
         av_add_index_entry(st, pos, timestamp, size, 0, AVINDEX_KEYFRAME);
         if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
-            timestamp += size / (st->codecpar->channels * 2);
+            timestamp += size / (st->codecpar->channels * 2LL);
         } else {
             timestamp++;
         }
@@ -353,7 +353,7 @@ static int mv_read_header(AVFormatContext *avctx)
             avio_skip(pb, 8);
             av_add_index_entry(ast, pos, timestamp, asize, 0, AVINDEX_KEYFRAME);
             av_add_index_entry(vst, pos + asize, i, vsize, 0, AVINDEX_KEYFRAME);
-            timestamp += asize / (ast->codecpar->channels * 2);
+            timestamp += asize / (ast->codecpar->channels * 2LL);
         }
     } else if (!version && avio_rb16(pb) == 3) {
         avio_skip(pb, 4);