[FFmpeg-cvslog] dxa: check reference frame availability before use.

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Fri Nov 30 20:58:26 2012 +0100| [7205e896a1ceb0e5c0256ed9cc1f69cf1fe664d4] | committer: Michael Niedermayer

dxa: check reference frame availability before use.

Fix 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=7205e896a1ceb0e5c0256ed9cc1f69cf1fe664d4
---

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

diff --git a/libavcodec/dxa.c b/libavcodec/dxa.c
index d43e113..cf8ce0c 100644
--- a/libavcodec/dxa.c
+++ b/libavcodec/dxa.c
@@ -270,6 +270,10 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPac
     case 13:
         c->pic.key_frame = 0;
         c->pic.pict_type = AV_PICTURE_TYPE_P;
+        if (!c->prev.data[0]) {
+            av_log(avctx, AV_LOG_ERROR, "Missing reference frame\n");
+            return AVERROR_INVALIDDATA;
+        }
         decode_13(avctx, c, c->pic.data[0], srcptr, c->prev.data[0]);
         break;
     default: