[PATCH 09/10] drm/etnaviv: validate readback register address

[Russell King - ARM Linux]

On Mon, Jan 30, 2017 at 11:58:32AM +0100, Lucas Stach wrote:
> Am Freitag, den 09.12.2016, 12:21 +0100 schrieb Christian Gmeiner:
> > Reading some registers end in a system crash ala:
> > 
> >   Unhandled fault: external abort on non-linefetch (0x1028) at 0xfe641000
> >   Internal error: : 1028 [#1] PREEMPT ARM
> > 
> > Avoid those by register validation.
> 
> Avoiding crashes is one thing, but I believe this needs to go further
> and avoid reads from any register that isn't a performance counter. This
> probably isn't a big hole, but we want to avoid leaking the GPU state to
> userspace.

We certainly don't want to let people use this to read stuff like the
ID registers, bypassing the kernel.

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