From 6b0565e5b8f4a39e8348cbb61c21727d098013a5 Mon Sep 17 00:00:00 2001
From: Laurent Aimar <fenrir@videolan.org>
Date: Tue, 27 Sep 2011 23:43:57 +0200
Subject: [PATCH] Prevent NULL dereferences when missing the reference frame in
 the xan decoder.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 19e95b88459e879d3e67a66350d937c32ed762ca)
---
 libavcodec/xan.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/xan.c b/libavcodec/xan.c
index 357593bf2d..404f4d10c6 100644
--- a/libavcodec/xan.c
+++ b/libavcodec/xan.c
@@ -222,6 +222,8 @@ static inline void xan_wc3_copy_pixel_run(XanContext *s,
 
     palette_plane = s->current_frame.data[0];
     prev_palette_plane = s->last_frame.data[0];
+    if (!prev_palette_plane)
+        prev_palette_plane = palette_plane;
     stride = s->current_frame.linesize[0];
     line_inc = stride - width;
     curframe_index = y * stride + x;