[FFmpeg-cvslog] avutil/timecode: Avoid undefined behavior with large framenum

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Nov 28 21:31:16 2020 +0100| [1b1905739638c22b476c99c679b41f29fa00bf07] | committer: Michael Niedermayer

avutil/timecode: Avoid undefined behavior with large framenum

Fixes: signed integer overflow: 2147462079 + 2149596 cannot be represented in type 'int'
Fixes: 27565/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5091972813160448

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1b1905739638c22b476c99c679b41f29fa00bf07
---

 libavutil/timecode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavutil/timecode.c b/libavutil/timecode.c
index 5106f642b9..280e4cacfb 100644
--- a/libavutil/timecode.c
+++ b/libavutil/timecode.c
@@ -46,7 +46,7 @@ int av_timecode_adjust_ntsc_framenum2(int framenum, int fps)
     d = framenum / frames_per_10mins;
     m = framenum % frames_per_10mins;
 
-    return framenum + 9 * drop_frames * d + drop_frames * ((m - drop_frames) / (frames_per_10mins / 10));
+    return framenum + 9U * drop_frames * d + drop_frames * ((m - drop_frames) / (frames_per_10mins / 10));
 }
 
 uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum)