From 43c34675afee8ced294ecc436f58587e8e8e913b Mon Sep 17 00:00:00 2001
From: Daniel Kang <daniel.d.kang@gmail.com>
Date: Mon, 10 Jan 2011 10:28:06 +0000
Subject: [PATCH] Check for invalid motion vector, fixes issue 2521.

Patch by Daniel Kang, daniel.d.kang at gmail

Originally committed as revision 26293 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/roqvideo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/roqvideo.c b/libavcodec/roqvideo.c
index 830eb7b329..eb8fc253ad 100644
--- a/libavcodec/roqvideo.c
+++ b/libavcodec/roqvideo.c
@@ -115,6 +115,11 @@ static inline void apply_motion_generic(RoqContext *ri, int x, int y, int deltax
         return;
     }
 
+    if (ri->last_frame->data[0] == NULL) {
+        av_log(ri->avctx, AV_LOG_ERROR, "Invalid decode type. Invalid header?\n");
+        return;
+    }
+
     for(cp = 0; cp < 3; cp++) {
         int outstride = ri->current_frame->linesize[cp];
         int instride  = ri->last_frame   ->linesize[cp];