Re: glibc: causes segfault in Xorg
On Mit, 2011-05-04 at 00:10 -0500, Jonathan Nieder wrote:
> Steve M. Robbins wrote:
> > Xorg now segfaults, with the following in the Xorg.0.log:
> > 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 ()
> Sounds like http://sourceware.org/bugzilla/show_bug.cgi?id=12518
> which is fixed (sort of) by commit 0354e355 (2011-04-01).
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.
Earthling Michel Dänzer | http://www.vmware.com
Libre software enthusiast | Debian, X and DRI developer