[FFmpeg-cvslog] wmavoice: validate block alignment

[Andreas Cadhalpun]

ffmpeg | branch: master | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Sun Jan  1 22:48:38 2017 +0100| [e8651f51aa46268613b328c60079e16d992e013f] | committer: Andreas Cadhalpun

wmavoice: validate block alignment

This prevents a division by zero crash in wmavoice_decode_packet.

The problem was introduced by commit
3deb4b54a24f8cddce463d9f5751b01efeb976af.

Reviewed-by: Ronald S. Bultje <rsbultje at gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=e8651f51aa46268613b328c60079e16d992e013f
---

 libavcodec/wmavoice.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/wmavoice.c b/libavcodec/wmavoice.c
index c310b19..c2390a9 100644
--- a/libavcodec/wmavoice.c
+++ b/libavcodec/wmavoice.c
@@ -388,6 +388,11 @@ static av_cold int wmavoice_decode_init(AVCodecContext *ctx)
                ctx->extradata_size);
         return AVERROR_INVALIDDATA;
     }
+    if (ctx->block_align <= 0) {
+        av_log(ctx, AV_LOG_ERROR, "Invalid block alignment %d.\n", ctx->block_align);
+        return AVERROR_INVALIDDATA;
+    }
+
     flags                = AV_RL32(ctx->extradata + 18);
     s->spillover_bitsize = 3 + av_ceil_log2(ctx->block_align);
     s->do_apf            =    flags & 0x1;