[FFmpeg-cvslog] avcodec/wmalosslessdec: Check block_align

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Oct 19 19:18:18 2019 +0200| [c1c799271eefb8afe22804a710baa5cbaad57d91] | committer: Michael Niedermayer

avcodec/wmalosslessdec: Check block_align

Fixes: NULL pointer dereference
Fixes: 18331/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMALOSSLESS_fuzzer-5652847445671936

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=c1c799271eefb8afe22804a710baa5cbaad57d91
---

 libavcodec/wmalosslessdec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index eb1db615ae..19bac949d4 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -184,8 +184,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
     unsigned int channel_mask;
     int i, log2_max_num_subframes;
 
-    if (!avctx->block_align) {
-        av_log(avctx, AV_LOG_ERROR, "block_align is not set\n");
+    if (avctx->block_align <= 0) {
+        av_log(avctx, AV_LOG_ERROR, "block_align is not set or invalid\n");
         return AVERROR(EINVAL);
     }