xserver -- multiple issue with X client request handling

Alan Coopersmith reports:

Ilja van Sprundel, a security researcher with IOActive, has
discovered a large number of issues in the way the X server
code base handles requests from X clients, and has worked
with X.Org’s security team to analyze, confirm, and fix
these issues.
The vulnerabilities could be exploited to cause the X server
to access uninitialized memory or overwrite arbitrary memory
in the X server process. This can cause a denial of service
(e.g., an X server segmentation fault), or could be exploited
to achieve arbitrary code execution.
The GLX extension to the X Window System allows an X client
to send X protocol to the X server, to request that the X
server perform OpenGL rendering on behalf of the X client.
This is known as “GLX indirect rendering”, as opposed to
“GLX direct rendering” where the X client submits OpenGL
rendering commands directly to the GPU, bypassing the X
server and avoiding the X server code for GLX protocol
handling.
Most GLX indirect rendering implementations share some
common ancestry, dating back to “Sample Implementation”
code from Silicon Graphics, Inc (SGI), which SGI
originally commercially licensed to other Unix workstation
and graphics vendors, and later released as open source, so
those vulnerabilities may affect other licensees of SGI’s
code base beyond those running code from the X.Org Foundation
or the XFree86 Project.