[FFmpeg-cvslog] avcodec/mpeg12dec: Fixes runtime error: division by zero

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu May 11 00:49:31 2017 +0200| [c0ece1f4addf8ac31df95775a2d36be2a55fc759] | committer: Michael Niedermayer

avcodec/mpeg12dec: Fixes runtime error: division by zero

Fixes: 1464/clusterfuzz-testcase-minimized-4925445571084288

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c0ece1f4addf8ac31df95775a2d36be2a55fc759
---

 libavcodec/mpeg12dec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index e49167f89e..186fbd27b6 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -1242,7 +1242,8 @@ static int mpeg_decode_postinit(AVCodecContext *avctx)
 
     if (avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
         // MPEG-1 aspect
-        avctx->sample_aspect_ratio = av_d2q(1.0 / ff_mpeg1_aspect[s->aspect_ratio_info], 255);
+        AVRational aspect_inv = av_d2q(ff_mpeg1_aspect[s->aspect_ratio_info], 255);
+        avctx->sample_aspect_ratio = (AVRational) { aspect_inv.den, aspect_inv.num };
     } else { // MPEG-2
         // MPEG-2 aspect
         if (s->aspect_ratio_info > 1) {