[FFmpeg-cvslog] ogg: fix double free when finding length of small chained oggs.

[Ronald S. Bultje]

ffmpeg | branch: release/0.8 | Ronald S. Bultje <rsbultje at gmail.com> | Tue Jun 28 22:24:21 2011 -0700| [8f7f3f0453dfe3a14b70bae28301a2ee661fc3f4] | committer: Carl Eugen Hoyos

ogg: fix double free when finding length of small chained oggs.

ogg_save() copies streams[], but doesn't keep track of free()'ed
struct members. Thus, if in between a call to ogg_save() and
ogg_restore(), streams[].private was free()'ed, this would result
in a double free -> crash, which happened when e.g. playing small
chained ogg fragments.
(cherry picked from commit 9ed6cbc3ee2ae3e7472fb25192a7e36fd7b15533)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8f7f3f0453dfe3a14b70bae28301a2ee661fc3f4
---

 libavformat/oggdec.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 655da35..dc9f7b6 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -240,7 +240,8 @@ static int ogg_read_page(AVFormatContext *s, int *str)
 
             for (n = 0; n < ogg->nstreams; n++) {
                 av_freep(&ogg->streams[n].buf);
-                av_freep(&ogg->streams[n].private);
+                if (!ogg->state || ogg->state->streams[n].private != ogg->streams[n].private)
+                    av_freep(&ogg->streams[n].private);
             }
             ogg->curidx   = -1;
             ogg->nstreams = 0;