[FFmpeg-cvslog] alsdec: check opt_order.

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Mar 24 01:39:13 2012 +0100| [9853e41aa0a6cfff629ff7009685eb8bf8d64e7f] | committer: Justin Ruggles

alsdec: check opt_order.

Fixes out of array write in quant_cof.
Also make sure no invalid opt_order stays in the context.

Fixes CVE-2012-2775

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
Signed-off-by: Justin Ruggles <justin.ruggles at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9853e41aa0a6cfff629ff7009685eb8bf8d64e7f
---

 libavcodec/alsdec.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index ef12253..defe3c4 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -668,6 +668,11 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
             int opt_order_length = av_ceil_log2(av_clip((bd->block_length >> 3) - 1,
                                                 2, sconf->max_order + 1));
             *bd->opt_order       = get_bits(gb, opt_order_length);
+            if (*bd->opt_order > sconf->max_order) {
+                *bd->opt_order = sconf->max_order;
+                av_log(avctx, AV_LOG_ERROR, "Predictor order too large!\n");
+                return AVERROR_INVALIDDATA;
+            }
         } else {
             *bd->opt_order = sconf->max_order;
         }