Re: [Xen-devel] Is Xen affected by this x86 hardware security hole?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 2 May 2006, at 14:10, Mark Williamson wrote:

> * X running in dom0 can, in principle, subvert any domain you're 
> running, if X
> itself gets subverted.  A bug in X in dom0 could hang the machine in
> principle.
Yes, although you are a little better off on Xen -- for example iopl==3 
doesn't let you disable interrupts, as it does on native. However, the 
X server will still have access to most I/O ports and can certainly 
wreak havoc because of that.
For this specific problem, it would make sense to ensure that D_LCK is 
set during boot, so that noone can thereafter modify the SMM memory 
space. You need to know something about PCI space to do that, though, 
so it would make sense for us to leave that to domain0.
 -- Keir


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