[FFmpeg-cvslog] smc: fix the bounds check

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Fri Oct  3 22:50:45 2014 +0200| [d423dd72be451462c6fb1cbbe313bed0194001ab] | committer: Anton Khirnov

smc: fix the bounds check

Fixes invalid writes when there are more blocks in a run than total
remaining blocks.

CC: libav-stable at libav.org
Bug-ID: CVE-2014-8548
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Anton Khirnov <anton at khirnov.net>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d423dd72be451462c6fb1cbbe313bed0194001ab
---

 libavcodec/smc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/smc.c b/libavcodec/smc.c
index 46903ab..c6541da 100644
--- a/libavcodec/smc.c
+++ b/libavcodec/smc.c
@@ -70,7 +70,7 @@ typedef struct SmcContext {
         row_ptr += stride * 4; \
     } \
     total_blocks--; \
-    if (total_blocks < 0) \
+    if (total_blocks < !!n_blocks) \
     { \
         av_log(s->avctx, AV_LOG_INFO, "warning: block counter just went negative (this should not happen)\n"); \
         return; \