Bug#625521: glibc: causes segfault in Xorg

[Jonathan Nieder <jrnieder@gmail.com>]

Hi,

Michel Dänzer wrote:
> On Mit, 2011-05-04 at 00:10 -0500, Jonathan Nieder wrote: 
>> Steve M. Robbins wrote:

>>> Program received signal SIGSEGV, Segmentation fault.
>>> __memcpy_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:153
>>> 153     ../sysdeps/x86_64/multiarch/memcpy-ssse3.S: No such file or directory.
>>>         in ../sysdeps/x86_64/multiarch/memcpy-ssse3.S
>>> (gdb) bt
>>> #0  __memcpy_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:153
>>> #1  0x00007ffff3858db1 in shadowUpdatePacked () from /usr/lib/xorg/modules/libshadow.so
>>> #2  0x00007ffff385843f in ?? () from /usr/lib/xorg/modules/libshadow.so
>>> #3  0x000000000043571d in BlockHandler ()
>>> #4  0x000000000045dcda in WaitForSomething ()
>>> #5  0x00000000004314b2 in ?? ()
>>> #6  0x00000000004257de in _start ()
[...]
> The purpose of shadowUpdatePacked is to copy pixels from a shadow
> framebuffer to the visible screen. It would be rather pointless for the
> shadow framebuffer to be contained within the visible screen, so
> shadowUpdatePacked should always be able to safely use memcpy as far as
> overlapping areas is concerned.
>
> If shadowUpdatePacked is indeed calling memcpy for overlapping areas
> here, that's probably a bug in the X driver being used.

Thanks, Michel.  Steve, could you install xserver-xorg-video-radeon-dbg
and get a full backtrace (bt full), or even better, run xorg under
valgrind and see what it says?