Bug#538082: Segmentation fault in avg_pixels8_xy2_altivec()

[Christian E. Böhme]

Package: libavcodec52
Version: 4:0.5+svn20090609-1
Severity: important



-- System Information:
Debian Release: squeeze/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: powerpc (ppc)

Kernel: Linux 2.6.19.7-tibookIV-fbc-xfs+ext2 (PREEMPT)
Locale: LANG=POSIX, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages libavcodec52 depends on:
ii  libavutil49          4:0.5+svn20090609-1 ffmpeg utility library
ii  libc6                2.9-12              GNU C Library: Shared libraries
ii  libfaad0             2.6.1-3.1           freeware Advanced Audio Decoder - 
ii  libgsm1              1.0.12-1            Shared libraries for GSM speech co
ii  libopenjpeg2         1.3+dfsg-4          JPEG 2000 image compression/decomp
ii  libschroedinger-1.0- 1.0.7-1             library for encoding/decoding of D
ii  libspeex1            1.2~rc1-1           The Speex codec runtime library
ii  libtheora0           1.0-2               The Theora Video Compression Codec
ii  libvorbis0a          1.2.0.dfsg-5        The Vorbis General Audio Compressi
ii  libvorbisenc2        1.2.0.dfsg-5        The Vorbis General Audio Compressi
ii  zlib1g               1:1.2.3.3.dfsg-13   compression library - runtime

libavcodec52 recommends no packages.

libavcodec52 suggests no packages.

-- no debconf information


Running any of the various video playback programs such as vlc or gxine
(I happen to use the latter) has them crash due to invalid memory access(es)
from within the /usr/lib/altivec/libavcodec.so.52 du jour.

As an example, open and play the video file that is available via the
attached torrent (these are the only files that cause the errors, BTW).
Executing gxine from withing gdb, in particular, yields the following
lines at a crash:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x35a51480 (LWP 2996)]
0x0e07a8b4 in avg_pixels8_altivec () from /usr/lib/altivec/libavcodec.so.52

The behaviour is reproducible in that it causes a crash but varies in the
time it takes for the seg fault to occur (usually within the fist two to three
minutes, occasionally longer) unless a fast forward or backward (via the
progress bar slider simultaneously acting as a random access control)
is attempted in which case the program bombs immediately.
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