[FFmpeg-cvslog] avformat/wavdec: Check block_align vs. channels before combining them

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Jan 17 23:16:46 2021 +0100| [0af0a80cef0eae709b727896e92b44382c3feca8] | committer: Michael Niedermayer

avformat/wavdec: Check block_align vs. channels before combining them

Fixes: signed integer overflow: 65535 * 65312 cannot be represented in type 'int'
Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_WAV_fuzzer-6606935226974208

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=0af0a80cef0eae709b727896e92b44382c3feca8
---

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

diff --git a/libavformat/wavdec.c b/libavformat/wavdec.c
index 2fba9a08c8..256c36ebe2 100644
--- a/libavformat/wavdec.c
+++ b/libavformat/wavdec.c
@@ -643,7 +643,8 @@ break_loop:
     } else if (st->codecpar->codec_id == AV_CODEC_ID_XMA1 ||
                st->codecpar->codec_id == AV_CODEC_ID_XMA2) {
         st->codecpar->block_align = 2048;
-    } else if (st->codecpar->codec_id == AV_CODEC_ID_ADPCM_MS && st->codecpar->channels > 2) {
+    } else if (st->codecpar->codec_id == AV_CODEC_ID_ADPCM_MS && st->codecpar->channels > 2 &&
+               st->codecpar->block_align < INT_MAX / st->codecpar->channels) {
         st->codecpar->block_align *= st->codecpar->channels;
     }