RHBA-2014:1591 - Bug Fix Advisory

Topic

Updated gdm packages that fix several bugs are now available for Red Hat
Enterprise Linux 6.

Description

The GNOME Display Manager (GDM) provides the graphical login screen, shown
shortly after boot up, log out, and when user-switching.

This update fixes the following bugs:

• Due to the bugs in the XDMCP remote desktop protocol chooser and indirect

query code, deadlocks and incorrect size arguments occurred on GDM. As a
consequence, the host chooser failed to properly delegate to other hosts. To fix
this bug, correct-size information is now used, and the recursive deadlock has
been removed. As a result, the indirect chooser now works more reliably.
(BZ#827257)

• Previously, the logic for determining when to force the X server to run on

virtual console 1 was inadequate, which caused the login screen and subsequent
user sessions to switch to virtual console 7 after the initial logout. This
update introduces a change in the logic to make virtual console 1 use the
statically hardwired display. Now, only auxiliary displays needed for user
switching run on virtual console 7 and above, and the main login screen with
subsequent user sessions always runs on virtual console 1. (BZ#992907)

• Prior to this update, the "Switch User" menu item depended on the GDM display

manager for starting a login screen. Consequently, the "Switch User" menu item
terminated unexpectedly if the user initially logged in with KDM. With this
update, the broken "Switch User" menu item is hidden if the user has not logged
in with GDM. (BZ#1004484)

• Due to a missing NULL check in the code, a benign error was logged in the

slave log file when logging in via a remote XDMCP connection. The missing NULL
check has been added to fix this bug, and error messages are no longer returned.
(BZ#1004909)

• Previously, GDM failed to create xauth entries usable by remote X clients.

Consequently, remote clients could not gain access to the host X server without
resorting to ssh tunnels. With this update, GDM writes out xauth entries
suitable for remote clients when the DisallowTCP option is set to "false" in the
configuration. As a result, xauth entries usable by remote clients are now
successfully generated. (BZ#1013351)

• When debugging was enabled and DNS misconfigured, errors in debug logging code

made GDM enter an infinite loop. As a consequence, the XDMCP remote desktop
protocol did not work or worked sporadically when debug mode was enabled; debug
code printed NULL instead of remote server host in failure scenarios. To fix
this bug, the debug code has been changed not to call itself and not to nullify
or leak the host name. As a result, GDM no longer locks up and returns more
comprehensible error messages. (BZ#1030163)

• Due to incorrect handling of the machine state in user switching code, user

switching applet could terminate unexpectedly shortly after login. With this
update, the machine state is handled differently, and user switching applet
crashes no longer occur. (BZ#1048769)

• If the window manager attempted to focus a window before user interaction,

benign warning messages were logged in the /var/log/gdm/:0-greeter.log file.
With this update, window focusing in the early start up is avoided, and the
window manager no longer returns warning messages. (BZ#1073546)

Users of gdm are advised to upgrade to these updated packages, which fix these
bugs. GDM must be restarted for this update to take effect. Rebooting achieves
this, but changing the runlevel from 5 to 3 and back to 5 also restarts GDM.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 992907 - Gray start bar of rhel shows in first text terminal of the rhel guest when send key Ctrl+Alt+Backspace followed by Ctrl+Alt+F2
• BZ - 1004484 - Unable to fast switch users from gnome when using KDM
• BZ - 1030163 - gdm fails to answer XDMCP queries when DNS is not configured
• BZ - 1048769 - "User Switcher" has quit unexpectedly

CVEs

(none)

References

(none)