[mythtv] segfault problem with current CVS.

[Chris Pinkham]

I'm receiving a segfault running current CVS code and was wondering if
anyone else was noticing or receiving this.

Occasionally when exiting playback or the playback list screen (in MythTV),
I will get a segfault.  I tried running using under gdb with
MALLOC_CHECK_=2 one time and with electric fence the other time.  Both
pointed back to a line in libavcodec trying to free memory.  I'm assuming
this is a pointer that has already been freed or was somehow changed to
point to different memory and can't be freed now.

In MC/libs/libavcodec/mpegvideo.c around line 363 you'll find a line like
this:

    av_freep(&pic->mbskip_table);

That's the line it's segfaulting on.  If I comment out that line (just to
test), then it just segfaults later so obviously something is seriously
hosed.

Isaac (or anyone else), can you point me in the right direction to see
where the problem might be occuring.  I'm seeing it even when I don't use
the commercial skip feature so I'm wondering if it's an unrelated problem.

I'm still working on trying to figure out how the libavcoded code
allocates/deallocates/uses memory during the whole decoding process but
haven't seen enough yet to know where to look to see if somehow this is
being re-freed or what.

Any pointers would be greatly appreciated.  I want to make sure this isn't
in the current commercial skip stuff before I modify it further with my new
patch.

Chris

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** Chris Pinkham                  Linux v2.2.18, Sane v1.0.4, Cajun v3.0-8 **
** cpinkham at bc2va.org                          http://www.bc2va.org/chris/ **
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