Fix invalid reads in VC1 decoder
Patch discussed and taken from https://roundup.ffmpeg.org/issue2584
(cherry picked from commit 2bbec1eda46d907605772a8b6e8263caa4bc4c82)
Change related to CVE-2011-0723
diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index 03257b8..619e903 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -2366,7 +2366,7 @@
if (index != vc1_ac_sizes[codingset] - 1) {
run = vc1_index_decode_table[codingset][index][0];
level = vc1_index_decode_table[codingset][index][1];
- lst = index >= vc1_last_decode_table[codingset];
+ lst = index >= vc1_last_decode_table[codingset] || get_bits_left(gb) < 0;
if(get_bits1(gb))
level = -level;
} else {
