[FFmpeg-cvslog] matroska: Update the available size after lace parsing

[Dale Curtis]

ffmpeg | branch: release/1.1 | Dale Curtis <dalecurtis at chromium.org> | Wed Mar 27 14:02:03 2013 -0700| [b90816d94b0b5c01f451ff98cfbf1d5ddec9c3c1] | committer: Reinhard Tartler

matroska: Update the available size after lace parsing

Fix heap-buffer-overflow in matroska_parse_block for
corrupted real media in mkv files.

CC: libav-stable at libav.org

Signed-off-by: Luca Barbato <lu_zero at gentoo.org>
(cherry picked from commit fc43c19a567aa945398dccb491d972c11ec2a065)

Signed-off-by: Reinhard Tartler <siretart at tauware.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b90816d94b0b5c01f451ff98cfbf1d5ddec9c3c1
---

 libavformat/matroskadec.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 962493c..5e94b72 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1757,10 +1757,10 @@ static void matroska_clear_queue(MatroskaDemuxContext *matroska)
 }
 
 static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,
-                                int size, int type,
+                                int* buf_size, int type,
                                 uint32_t **lace_buf, int *laces)
 {
-    int res = 0, n;
+    int res = 0, n, size = *buf_size;
     uint8_t *data = *buf;
     uint32_t *lace_size;
 
@@ -1858,6 +1858,7 @@ static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,
 
     *buf      = data;
     *lace_buf = lace_size;
+    *buf_size = size;
 
     return res;
 }
@@ -2052,7 +2053,7 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
         matroska->skip_to_keyframe = 0;
     }
 
-    res = matroska_parse_laces(matroska, &data, size, (flags & 0x06) >> 1,
+    res = matroska_parse_laces(matroska, &data, &size, (flags & 0x06) >> 1,
                                &lace_size, &laces);
 
     if (res)