[FFmpeg-cvslog] Fix potential overread in vmd audio decoder.

[Laurent Aimar]

ffmpeg | branch: master | Laurent Aimar <fenrir at videolan.org> | Sat Sep 24 23:16:17 2011 +0200| [00cbe9e4053fd562b6f21e76aca6636ff926b637] | committer: Michael Niedermayer

Fix potential overread in vmd audio decoder.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=00cbe9e4053fd562b6f21e76aca6636ff926b637
---

 libavcodec/vmdav.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/libavcodec/vmdav.c b/libavcodec/vmdav.c
index 9197891..77e0432 100644
--- a/libavcodec/vmdav.c
+++ b/libavcodec/vmdav.c
@@ -523,7 +523,10 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
 
     silent_chunks = 0;
     if (block_type == BLOCK_TYPE_INITIAL) {
-        uint32_t flags = AV_RB32(buf);
+        uint32_t flags;
+        if (buf_size < 4)
+            return -1;
+        flags = AV_RB32(buf);
         silent_chunks  = av_popcount(flags);
         buf      += 4;
         buf_size -= 4;