GDM: Local Denial of Service

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200709-11 / gdm
Release Date	September 18, 2007
Latest Revision	September 18, 2007: 01
Impact	low
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
gnome-base/gdm	< 2.18.4	>= 2.18.4, revision >= 2.16.7	All supported architectures

Related bugreports: #187919

Synopsis

GDM can be crashed by a local user, preventing it from managing future displays.

2. Impact Information

Background

GDM is the GNOME display manager.

Description

The result of a g_strsplit() call is incorrectly parsed in the files daemon/gdm.c, daemon/gdmconfig.c, gui/gdmconfig.c and gui/gdmflexiserver.c, allowing for a null pointer dereference.

Impact

A local user could send a crafted message to /tmp/.gdm_socket that would trigger the null pointer dereference and crash GDM, thus preventing it from managing future displays.

3. Resolution Information

Workaround

Restrict the write permissions on /tmp/.gdm_socket to trusted users only after each GDM restart.

Resolution

All GDM users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose "gnome-base/gdm"

4. References

CVE-2007-3381

Page updated September 18, 2007

Summary: This is a Gentoo Linux Security Advisory

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