[Ffmpeg-devel] segfault in ff_mpeg1_find_frame_end()

Stefan Lucke stefan
Thu Apr 14 10:13:37 CEST 2005

Quoting The Wanderer <inverseparadox at comcast.net>:

> Stefan Lucke wrote:
> > On Sonntag, 10. April 2005 22:12, M?ns Rullg?rd wrote:
> >> All signs are pointing at some buffer misuse.  Could you try
> >> running it under valgrind?
> >
> > Ok, thats no with valgrind 2.4.0. Before calling
> > avcodec_decode_video() I still do a extra copy like this (valgrind
> > --tool=addrcheck):
> <snip>
> > When reaching the 16:9 to 4:3 transition valgrind starts talking:
> <snip>
> > and so on. Is there a way to get the line numbers ? ffmpeg is
> > compiled with " -g " . The same is reported for my uploaded sample
> > stream.
> If I'm not mistaken, you need to use the binary ffmpeg_g, which contains
> debugging symbols (line numbers, etc.) and is generated unless the
> --disable-debug flag is passed to configure. It should be located in the
> root of the ffmpeg source tree.

Thanks for your reply, but my words were misleading. I did not binary ffmpeg.
I did run valgrind --tools=addrcheck ./vdr -P "softdevice ...." .
Plain ffmpeg valgrind is pending.

In between I had a look at ff_combine_frame() of file parser.c which does a
av_fast_realloc() with FF_INPUT_BUFFER_PADDING_SIZE additional bytes. But
these additional bytes are not zeroed as comment in avcodec.h claims.
I'll have to check if that might cause my segfaults.

Stefan Lucke

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