Created attachment 796457 [details]
backtrace

Description of problem:
Connecting through XDMCP to a remote machine sometimes ends up in a crash with the following backtrace in the terminal (refer to the attachment for a backtrace from gdb). I've managed to reproduce this only on ppc64 arch but it may not be arch-specific.


(EE) 
(EE) Backtrace:
(EE) 0: Xephyr (xorg_backtrace+0x36) [0x464fb6]
(EE) 1: Xephyr (0x400000+0x6ad19) [0x46ad19]
(EE) 2: /lib64/libpthread.so.0 (0x3e1d800000+0xf500) [0x3e1d80f500]
(EE) 3: /lib64/libc.so.6 (memcpy+0x2eb) [0x3e1d489b0b]
(EE) 4: Xephyr (0x400000+0x16de52) [0x56de52]
(EE) 5: Xephyr (0x400000+0x17689d) [0x57689d]
(EE) 6: Xephyr (0x400000+0x1772a5) [0x5772a5]
(EE) 7: Xephyr (0x400000+0x30059) [0x430059]
(EE) 8: Xephyr (0x400000+0x9397a) [0x49397a]
(EE) 9: /lib64/libc.so.6 (__libc_start_main+0xfd) [0x3e1d41ecdd]
(EE) 10: Xephyr (0x400000+0x1dba9) [0x41dba9]
(EE) 
(EE) Segmentation fault at address 0x1133000

Fatal server error:
Caught signal 11 (Segmentation fault). Server aborting


Version-Release number of selected component (if applicable):
xorg-x11-server-Xephyr-1.13.0-11.el6.x86_64

How reproducible:
random

Steps to Reproduce:
1. Put Enable=true under [xdmcp] section in /etc/gdm/custom.conf on the host
2. Restart GDM on the host (initctl restart prefdm)
3. Disable firewall on both the host and client machine
4. Connect from the client using: Xephyr :99 -query <host-ip>

Actual results:
At some point, before a remote GDM instance has finished loading, Xephyr crashes.

Expected results:
No crash.