Re: [Xen-devel] [PATCH] x86/msi: Validate the guest-identified PCI devices in pci_prepare_msix()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/01/14 09:49, Jan Beulich wrote:
>>>> On 22.01.14 at 05:31, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
>> See attached (and relevant part inlined).
>> ...
>> (XEN) [2014-01-22 12:27:07] Xen call trace:
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d0801683a2>] 
>> msix_capability_init+0x1dc/0x603
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d080168987>] 
>> pci_enable_msi+0x1be/0x4d7
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d08016c65c>] 
>> map_domain_pirq+0x222/0x5ad
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d08017f104>] 
>> physdev_map_pirq+0x507/0x5d1
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d08017f814>] 
>> do_physdev_op+0x646/0x119e
>> (XEN) [2014-01-22 12:27:07]    [<ffff82d08022231b>] syscall_enter+0xeb/0x145
>> (XEN) [2014-01-22 12:27:07] 
>> (XEN) [2014-01-22 12:27:07] Pagetable walk from 0000000000000004:
> Considering the similarity, this is surely another incarnation of
> the same issue. Which gets me to ask first of all - is the device
> being acted upon an MSI-X capable one? If not, why is the call
> being made? If so (and Xen thinks differently) that's what
> needs fixing.
>
> On that basis I'm also going to ignore your patch for the first
> problem, Andrew: It's either incomplete or unnecessary or
> fixing the wrong thing.
>
> Jan
>

I am going to go with incomplete - it is certainly not unnecessary.  The
PCI device parameters to pci_prepare_msix() are completely guest
controlled; There is no validation of the SBDF at all.

~Andrew

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