Re: preventing GPU reset DoS

[Dave A. <ai...@gm...>]

On Wed, Sep 23, 2009 at 5:13 AM, Pauli Nieminen <su...@gm...> wrote:
> Hi!
>
> I have been thinking GPU reset as possible DoS attack from
> user-space.Problem here is that display doesn't work anymore at all if
> attacker chooses to run a application that constantly causes GPU hang. It
> would be of course ideal to have CS checker not to let in any problematic
> combinations of commands. Butin practice we can't assume that everything is
> safe with all hardware so we need to take some actions prevent possible
> problems.
>
> So first defense would be terminating application that did send command
> stream that caused GPU hang. But attacker could easily by-pass this
> protection with forking all the time new processes.
>
> So we need stronger defense if same user account is causing multiple hangs
> in short time frame. I would think temporary denying new DRI access would
> let user to gain back control of system and take actions to stop the
> problematic program from running.
>

It depends on what sort of system you are talking about, in a normal
desktop/laptop user type systems, the DoS is either going to be
sitting at it in which case the power button, or caused by an app
running on it, possibly X, in which case killing it will solve the issue.

In a multi-user gpgpu environment, if someone starts a DoS, it
should only lock up the GPU not the CPU, unless the start a CPU
DoS as well, so in that case an admin can always ssh in and
kill the DoS user a/c etc.

I'm just wondering what other use-case we'd need anything more
agressive?

Dave.