[FFmpeg-cvslog] avcodec/alsdec: skip cases where the master channel equals the current channel

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Dec 28 23:53:24 2013 +0100| [5c74fa6ce0205c341afb76f6adf2b73c88ff26ef] | committer: Michael Niedermayer

avcodec/alsdec: skip cases where the master channel equals the current channel

Fixes: msan_uninit-mem_7f6c73c97cf9_3571_als_04_2ch48k16b.mp4
Fixes use of uninitialized memory
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Reviewed-by: Thilo Borgmann <thilo.borgmann at mail.de>
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5c74fa6ce0205c341afb76f6adf2b73c88ff26ef
---

 libavcodec/alsdec.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index f554eaa..c42b2ae 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1263,14 +1263,16 @@ static int revert_channel_correlation(ALSDecContext *ctx, ALSBlockData *bd,
     bd->quant_cof   = ctx->quant_cof[c];
     bd->raw_samples = ctx->raw_samples[c] + offset;
 
-    dep = 0;
-    while (!ch[dep].stop_flag) {
+    for (dep = 0; !ch[dep].stop_flag; dep++) {
         unsigned int smp;
         unsigned int begin = 1;
         unsigned int end   = bd->block_length - 1;
         int64_t y;
         int32_t *master = ctx->raw_samples[ch[dep].master_channel] + offset;
 
+        if (ch[dep].master_channel == c)
+            continue;
+
         if (ch[dep].time_diff_flag) {
             int t = ch[dep].time_diff_index;
 
@@ -1302,8 +1304,6 @@ static int revert_channel_correlation(ALSDecContext *ctx, ALSBlockData *bd,
                 bd->raw_samples[smp] += y >> 7;
             }
         }
-
-        dep++;
     }
 
     return 0;