[FFmpeg-cvslog] avformat/oggdec: Disable mid stream codec changes

[Michael Niedermayer]

ffmpeg | branch: release/4.3 | Michael Niedermayer <michael at niedermayer.cc> | Sat Jun 13 12:36:49 2020 +0200| [6011484167bf4a0548dedd0da573c4933cd335be] | committer: Michael Niedermayer

avformat/oggdec: Disable mid stream codec changes

Fixes: 22082/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5688619118624768
Fixes: crash from V-codecs/Theora/theora_testsuite_broken/multi2.ogg

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Suggested-by: Lynne on IRC
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 70277f12328fb052c2c758fa7f4eb36b9ea89638)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6011484167bf4a0548dedd0da573c4933cd335be
---

 libavformat/oggdec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 9eb45499c6..a456c3df60 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -226,9 +226,10 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, char *magic,
         return AVERROR_INVALIDDATA;
     }
 
-    /* We only have a single stream anyway, so if there's a new stream with
-     * a different codec just replace it */
     os = &ogg->streams[0];
+    if (os->codec != codec)
+        return AVERROR(EINVAL);
+
     os->serial  = serial;
     os->codec   = codec;
     os->serial  = serial;