[FFmpeg-cvslog] avcodec/wmaprodec: Check if there is a stream

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Oct  2 19:26:51 2019 +0200| [9b533de28eb19c660c75823ff2af2f8549c4095a] | committer: Michael Niedermayer

avcodec/wmaprodec: Check if there is a stream

Fixes: null pointer dereference
Fixes: signed integer overflow: 512 * 2147483647 cannot be represented in type 'int'
Fixes: 17809/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_XMA1_fuzzer-5634409947987968

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9b533de28eb19c660c75823ff2af2f8549c4095a
---

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

diff --git a/libavcodec/wmaprodec.c b/libavcodec/wmaprodec.c
index d0fa974c80..6ce2dd4adb 100644
--- a/libavcodec/wmaprodec.c
+++ b/libavcodec/wmaprodec.c
@@ -1902,7 +1902,9 @@ static av_cold int xma_decode_init(AVCodecContext *avctx)
     }
 
     /* encoder supports up to 64 streams / 64*2 channels (would have to alloc arrays) */
-    if (avctx->channels > XMA_MAX_CHANNELS || s->num_streams > XMA_MAX_STREAMS) {
+    if (avctx->channels > XMA_MAX_CHANNELS || s->num_streams > XMA_MAX_STREAMS ||
+        s->num_streams <= 0
+    ) {
         avpriv_request_sample(avctx, "More than %d channels in %d streams", XMA_MAX_CHANNELS, s->num_streams);
         return AVERROR_PATCHWELCOME;
     }