The (in)security of Xorg and DRI

[Darren Reed <avalon@caligula.anu.edu.au>]

In recent discussion, the topic of the Xorg server being a huge
security vulnerability because of its DRI model has come up.

The problem being that you have user space code communicating
with chips in the system and being able to control DMA and what
goes which way on the system bus...

Does anyone have or know of any security exploits that take
advantage of this model and use it to bypass other security
enforcing perimeters?  I'm imaging these to be dedicated
programs to run as root, not simple buffer overflows or
anything of that nature.

While this may not be of concern to the average Joe Bloggs at
home with his Linux desktop, if he were to be running a trusted
version of Linux with the same Xorg and DRI opening, the problem
is a tad different.

Cheers,
Darren