[FFmpeg-cvslog] vp6: Fix illegal read.

[Alex Converse]

ffmpeg | branch: release/0.8 | Alex Converse <alex.converse at gmail.com> | Thu Nov  3 15:55:52 2011 -0700| [93f1159af5221e23c749be8fa0d3df3ef7a93fd0] | committer: Michael Niedermayer

vp6: Fix illegal read.
(cherry picked from commit 2a6eb06254df79e96b3d791b6b89b2534ced3119)

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=93f1159af5221e23c749be8fa0d3df3ef7a93fd0
---

 libavcodec/vp6.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/libavcodec/vp6.c b/libavcodec/vp6.c
index 3721d52..c66d2e7 100644
--- a/libavcodec/vp6.c
+++ b/libavcodec/vp6.c
@@ -374,7 +374,7 @@ static void vp6_parse_coeff_huffman(VP56Context *s)
         if (b > 3) pt = 1;
         vlc_coeff = &s->dccv_vlc[pt];
 
-        for (coeff_idx=0; coeff_idx<64; ) {
+        for (coeff_idx = 0;;) {
             int run = 1;
             if (coeff_idx<2 && s->nb_null[coeff_idx][pt]) {
                 s->nb_null[coeff_idx][pt]--;
@@ -411,6 +411,8 @@ static void vp6_parse_coeff_huffman(VP56Context *s)
                 }
             }
             coeff_idx+=run;
+            if (coeff_idx >= 64)
+                break;
             cg = FFMIN(vp6_coeff_groups[coeff_idx], 3);
             vlc_coeff = &s->ract_vlc[pt][ct][cg];
         }