Description of problem:
Getting segfault only when running reproducer for CVE-2011-2895 (see https://bugzilla.redhat.com/show_bug.cgi?id=725760#c2), segfaulting on new packages only using Xephyr. Xorg, Xnest are fine. 

Version-Release number of selected component (if applicable):
libXfont-1.2.2-1.0.4.el5_7

How reproducible:
100%

Steps to Reproduce:
1. follow instructions at https://bugzilla.redhat.com/show_bug.cgi?id=725760#c2 
2.
3.
  
Actual results:
SIGSEGV

Expected results:
no segfault

Additional info:

Program received signal SIGSEGV, Segmentation fault.
__glXMesaScreenDestroy (screen=0x9d5b2e8) at xf86glx.c:299
299		if (mesaScreen->xm_vis[i])
#0  __glXMesaScreenDestroy (screen=0x9d5b2e8) at xf86glx.c:299
        i = 0
#1  0x08125527 in __glXResetScreens () at glxscreens.c:321
        i = 0
#2  0x0812476c in ResetExtension (extEntry=0x9d540c8) at glxext.c:49
No locals.
#3  0x080750a6 in CloseDownExtensions () at extension.c:280
        i = 20
        j = 0
#4  0x0807921f in main (argc=4, argv=0xbfb8a4c4, envp=0x2415e0) at main.c:453
        i = <value optimized out>
        error = 9076504
        xauthfile = <value optimized out>
        alwaysCheckForInput = {0, 1}
A debugging session is active.

	Inferior 1 [process 5407] will be detached.

Quit anyway? (y or n) LND: Sending signal 11 to process 5407
Detaching from program: /usr/bin/Xephyr, process 5407