[FFmpeg-cvslog] vc1dec: ensure cbpcy_vlc has been set before decoding a frame.

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Jan 12 03:40:54 2013 +0100| [cc548ea7a60355e15ed78431a55a896db074aa11] | committer: Michael Niedermayer

vc1dec: ensure cbpcy_vlc has been set before decoding a frame.

Fixes null pointer dereference

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=cc548ea7a60355e15ed78431a55a896db074aa11
---

 libavcodec/vc1dec.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index fa25161..7be1c8c 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -5711,6 +5711,10 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                 av_log(v->s.avctx, AV_LOG_ERROR, "end mb y %d %d invalid\n", s->end_mb_y, s->start_mb_y);
                 continue;
             }
+            if (!v->p_frame_skipped && s->pict_type != AV_PICTURE_TYPE_I && !v->cbpcy_vlc) {
+                av_log(v->s.avctx, AV_LOG_ERROR, "missing cbpcy_vlc\n");
+                continue;
+            }
             ff_vc1_decode_blocks(v);
             if (i != n_slices)
                 s->gb = slices[i].gb;