[SM-Security] [SMGLSA-2006-25] Xorg: Buffer overflow in the Xrender extension

[George sherwood]

Summary
============
A client of the X server using the X render extension is able to
send requests that will cause a buffer overflow in the server side of
the extension.
This overflow can be exploited by an authorized client to execute
malicious code inside the X server, which is generally running with
root privileges.

Impact
======
An unfortunate typo ('&' instead of '*' in an expression) causes the
code to mis-compute the size of memory allocations in the
XRenderCompositeTriStrip and XRenderCompositeTriFan requests. Thus a
buffer that may be too small is used to store the parameters of the
request. On platforms where the ALLOCATE_LOCAL() macro is using
alloca(), this is a stack overflow, on other platforms this is a heap
overflow.

Affected versions:
=========

X.Org 6.8.0 and later versions are vulnerable, as well as all individual
releases of the modular xorg-xserver package.

Solution:
=========
Update xorg as soon as possible.

Resolution
==========
All xorg users should upgrade to the latest available version:
# scribe update
# cast -c xorg

or

# scribe update
# sorcery queue-security
# cast --queue

References
============
http://lists.freedesktop.org/archives/xorg/2006-May/015136.html