[FFmpeg-cvslog] avformat/genh: Check block_align for how it will be used in SDX2_DPCM

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Oct 17 23:40:57 2020 +0200| [c95b47e18fdb43a4c667ae22a5d3a5ee6cf7782d] | committer: Michael Niedermayer

avformat/genh: Check block_align for how it will be used in SDX2_DPCM

Fixes: signed integer overflow: 19922944 * 1024 cannot be represented in type 'int'
Fixes: 26402/clusterfuzz-testcase-minimized-ffmpeg_dem_VMD_fuzzer-5745470053548032

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=c95b47e18fdb43a4c667ae22a5d3a5ee6cf7782d
---

 libavformat/genh.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/genh.c b/libavformat/genh.c
index 61adf49964..ed9910503d 100644
--- a/libavformat/genh.c
+++ b/libavformat/genh.c
@@ -87,7 +87,9 @@ static int genh_read_header(AVFormatContext *s)
     case  5: st->codecpar->codec_id = st->codecpar->block_align > 0 ?
                                    AV_CODEC_ID_PCM_S8_PLANAR :
                                    AV_CODEC_ID_PCM_S8;           break;
-    case  6: st->codecpar->codec_id = AV_CODEC_ID_SDX2_DPCM;        break;
+    case  6: if (st->codecpar->block_align > INT_MAX/1024)
+                 return AVERROR_INVALIDDATA;
+             st->codecpar->codec_id = AV_CODEC_ID_SDX2_DPCM;        break;
     case  7: ret = ff_alloc_extradata(st->codecpar, 2);
              if (ret < 0)
                  return ret;