RHEL 5 : xorg-x11-server (RHSA-2012:0303)

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Synopsis :

The remote Red Hat host is missing one or more security updates.

Description :

Updated xorg-x11-server packages that fix one security issue and
various bugs are now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having low
security impact. A Common Vulnerability Scoring System (CVSS) base
score, which gives a detailed severity rating, is available from the
CVE link in the References section.

X.Org is an open source implementation of the X Window System. It
provides the basic low-level functionality that full-fledged graphical
user interfaces are designed upon.

A flaw was found in the way the X.Org server handled lock files. A
local user with access to the system console could use this flaw to
determine the existence of a file in a directory not accessible to the
user, via a symbolic link attack. (CVE-2011-4028)

Red Hat would like to thank the researcher with the nickname vladz for
reporting this issue.

This update also fixes the following bugs :

* In rare cases, if the front and back buffer of the
miDbePositionWindow() function were not both allocated in video
memory, or were both allocated in system memory, the X Window System
sometimes terminated unexpectedly. A patch has been provided to
address this issue and X no longer crashes in the described scenario.
(BZ#596899)

* Previously, when the miSetShape() function called the
miRegionDestroy() function with a NULL region, X terminated
unexpectedly if the backing store was enabled. Now, X no longer
crashes in the described scenario. (BZ#676270)

* On certain workstations running in 32-bit mode, the X11 mouse cursor
occasionally became stuck near the left edge of the X11 screen. A
patch has been provided to address this issue and the mouse cursor no
longer becomes stuck in the described scenario. (BZ#529717)

* On certain workstations with a dual-head graphics adapter using the
r500 driver in Zaphod mode, the mouse pointer was confined to one
monitor screen and could not move to the other screen. A patch has
been provided to address this issue and the mouse cursor works
properly across both screens. (BZ#559964)

* Due to a double free operation, Xvfb (X virtual framebuffer)
terminated unexpectedly with a segmentation fault randomly when the
last client disconnected, that is when the server reset. This bug has
been fixed in the miDCCloseScreen() function and Xvfb no longer
crashes. (BZ#674741)

* Starting the Xephyr server on an AMD64 or Intel 64 architecture with
an integrated graphics adapter caused the server to terminate
unexpectedly. This bug has been fixed in the code and Xephyr no longer
crashes in the described scenario. (BZ#454409)

* Previously, when a client made a request bigger than 1/4th of the
limit advertised in the BigRequestsEnable reply, the X server closed
the connection unexpectedly. With this update, the maxBigRequestSize
variable has been added to the code to check the size of client
requests, thus fixing this bug. (BZ#555000)

* When an X client running on a big-endian system called the
XineramaQueryScreens() function, the X server terminated unexpectedly.
This bug has been fixed in the xf86Xinerama module and the X server no
longer crashes in the described scenario. (BZ#588346)

* When installing Red Hat Enterprise Linux 5 on an IBM eServer System
p blade server, the installer did not set the correct mode on the
built-in KVM (Keyboard-Video-Mouse). Consequently, the graphical
installer took a very long time to appear and then was displayed
incorrectly. A patch has been provided to address this issue and the
graphical installer now works as expected in the described scenario.
Note that this fix requires the Red Hat Enterprise Linux 5.8 kernel
update. (BZ#740497)

* Lines longer than 46,340 pixels can be drawn with one of the
coordinates being negative. However, for dashed lines, the
miPolyBuildPoly() function overflowed the 'int' type when setting up
edges for a section of a dashed line. Consequently, dashed segments
were not drawn at all. An upstream patch has been applied to address
this issue and dashed lines are now drawn correctly. (BZ#649810)

All users of xorg-x11-server are advised to upgrade to these updated
packages, which correct these issues. All running X.Org server
instances must be restarted for this update to take effect.

See also :

https://www.redhat.com/security/data/cve/CVE-2011-4028.html
http://rhn.redhat.com/errata/RHSA-2012-0303.html

Solution :

Update the affected packages.

Risk factor :

Low / CVSS Base Score : 1.2
(CVSS2#AV:L/AC:H/Au:N/C:P/I:N/A:N)
CVSS Temporal Score : 1.0
(CVSS2#E:ND/RL:OF/RC:C)
Public Exploit Available : true

Family: Red Hat Local Security Checks

Nessus Plugin ID: 58057 ()

Bugtraq ID: 50193

CVE ID: CVE-2011-4028