Re: Xen security advisory CVE-2011-1898 - VT-d (PCI passthrough) MSI

[Joanna Rutkowska <joanna@invisiblethingslab.com>]

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On 05/13/11 13:11, Ian Campbell wrote:
> On Fri, 2011-05-13 at 12:08 +0100, Joanna Rutkowska wrote:
>> On 05/13/11 10:08, Jan Beulich wrote:
> 
>>> Finally, wouldn't killing all guests that potentially could have caused
>>> the problem be a better measure than bringing down the host?
>>>
>>
>> Killing the guest might no longer be enough, because the guest might
>> have already programmed the device to keep sending malicious MSIs.
> 
> Is it even possible to know which guest triggered the MSI, or is the
> best you can do the set of all guests with an MSI capable device passed
> through?
> 

Ah, probably you're right -- if we have more than one driver domain,
then I think LAPIC would not tell us which device genrated the MSI.

In fact it's not really correct to assume that it must have been a guest
with a "MSI capable device" -- note that we don't trigger the MSI via
the official MSI triggering mechanism.

joanna.


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