[FFmpeg-cvslog] Fix writes out of bounds in the ogg demuxer.

[Laurent Aimar]

ffmpeg | branch: release/0.8 | Laurent Aimar <fenrir at videolan.org> | Sun Sep 11 23:37:44 2011 +0200| [be82df9e129995321917f47416ac755551915cb0] | committer: Michael Niedermayer

Fix writes out of bounds in the ogg demuxer.

Between ogg_save() and ogg_restore() calls, the number of streams
could have been reduced.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit bc851a2946c64eefb96145b70e2190ff7d5a4827)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=be82df9e129995321917f47416ac755551915cb0
---

 libavformat/oggdec.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index bb1df35..6ae4d80 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -29,7 +29,6 @@
     DEALINGS IN THE SOFTWARE.
 **/
 
-
 #include <stdio.h>
 #include "oggdec.h"
 #include "avformat.h"
@@ -93,14 +92,24 @@ static int ogg_restore(AVFormatContext *s, int discard)
     ogg->state = ost->next;
 
     if (!discard){
+        struct ogg_stream *old_streams = ogg->streams;
+
         for (i = 0; i < ogg->nstreams; i++)
             av_free (ogg->streams[i].buf);
 
         avio_seek (bc, ost->pos, SEEK_SET);
         ogg->curidx = ost->curidx;
         ogg->nstreams = ost->nstreams;
-        memcpy(ogg->streams, ost->streams,
-               ost->nstreams * sizeof(*ogg->streams));
+        ogg->streams = av_realloc (ogg->streams,
+                                   ogg->nstreams * sizeof (*ogg->streams));
+
+        if (ogg->streams) {
+            memcpy(ogg->streams, ost->streams,
+                   ost->nstreams * sizeof(*ogg->streams));
+        } else {
+            av_free(old_streams);
+            ogg->nstreams = 0;
+        }
     }
 
     av_free (ost);