yields a value for priv->bytes_per_line which is too small. priv->bytes_per_line is then used by Xephyr to create its host-side image data buffer (resulting in a buffer that is too small). Then, when Xephyr maps its root window, it segfaults by writing beyond the end of the too-small image data buffer while filling its root window in response to expose-event/damage processing.
As for fixes: ajax proposed one fix for this problem six months ago that seems to have gotten lost after an unanswered request for an amendment by keithp:
I tested this patch against Ubuntu's xserver-xorg_2:1.9.0-0ubuntu7 package (from Maverick) and can confirm that it fixed the segfault for me in that environment.
For the past year, distro bugtrackers have been receiving reports that Xephyr segfaults when it tries to map its client-facing root window:
https:/ /bugs.launchpad .net/ubuntu/ +source/ xorg-server/ +bug/635523 /bugzilla. redhat. com/show_ bug.cgi? id=518960 /qa.mandriva. com/show_ bug.cgi? id=47928
https:/
https:/
The cause of the problem is that, on some 24bpp hosts, this computation:
http:// cgit.freedeskto p.org/xorg/ xserver/ tree/hw/ kdrive/ ephyr/ephyr. c#n255
yields a value for priv->bytes_ per_line which is too small. priv->bytes_ per_line is then used by Xephyr to create its host-side image data buffer (resulting in a buffer that is too small). Then, when Xephyr maps its root window, it segfaults by writing beyond the end of the too-small image data buffer while filling its root window in response to expose-event/damage processing.
As for fixes: ajax proposed one fix for this problem six months ago that seems to have gotten lost after an unanswered request for an amendment by keithp:
http:// patchwork. freedesktop. org/patch/ 1327/
I tested this patch against Ubuntu's xserver- xorg_2: 1.9.0-0ubuntu7 package (from Maverick) and can confirm that it fixed the segfault for me in that environment.