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Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses |
Date: |
Mon, 17 Oct 2011 21:43:31 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Oct 17, 2011 at 09:11:29PM +0200, Jan Kiszka wrote:
> On 2011-10-17 14:50, Michael S. Tsirkin wrote:
> > On Mon, Oct 17, 2011 at 02:07:10PM +0200, Jan Kiszka wrote:
> >> On 2011-10-17 13:57, Michael S. Tsirkin wrote:
> >>> On Mon, Oct 17, 2011 at 01:23:46PM +0200, Jan Kiszka wrote:
> >>>> On 2011-10-17 13:10, Michael S. Tsirkin wrote:
> >>>>> On Mon, Oct 17, 2011 at 11:27:40AM +0200, Jan Kiszka wrote:
> >>>>>> Only accesses to the MSI-X table must trigger a call to
> >>>>>> msix_handle_mask_update or a notifier invocation.
> >>>>>>
> >>>>>> Signed-off-by: Jan Kiszka <address@hidden>
> >>>>>
> >>>>> Why would msix_mmio_write be called on an access
> >>>>> outside the table?
> >>>>
> >>>> Because it handles both the table and the PBA.
> >>>
> >>> Hmm. Interesting. Is there a bug in how we handle PBA
> >>> updates then? If yes I'd like a separate patch for that
> >>> to apply to the stable tree.
> >>
> >> I first thought it was a serious bug, but it just triggers if the guest
> >> write to PBA (which is very uncommon) and that actually triggers any
> >> spurious out-of-bounds vector injection. Highly unlikely.
> >
> > Yes guests don't really use PBA ATM. But is there something
> > bad a malicious guest can do? For example, what if
> > msix_clr_pending gets invoked with this huge vector value?
> >
> > It does seem serious ...
>
> I checked it before and I think it is harmless. The largest vector that
> can be miscalculated is 255. But bit 255 in the PBA is still safe inside
> our MMIO page.
>
> Jan
>
you are right. we got lucky.
- Re: [Qemu-devel] [RFC][PATCH 11/45] msi: Factor out delivery hook, (continued)
[Qemu-devel] [RFC][PATCH 13/45] hpet: Use msi_deliver, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 06/45] msix: Prevent bogus mask updates on MMIO accesses,
Michael S. Tsirkin <=
[Qemu-devel] [RFC][PATCH 09/45] msi: Factor out msi_message_from_vector, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 26/45] qemu-kvm: Use g_realloc for irq_routes extension, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 17/45] qemu-kvm: Track MSIRoutingCache in KVM routing table, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 04/45] msi: Invoke msi/msix_reset from PCI core, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 25/45] qemu-kvm: Update MSI cache on kvm_msi_irqfd_set, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 20/45] qemu-kvm: msix: Only invoke msix_handle_mask_update on changes, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 14/45] qemu-kvm: Drop useless kvm_clear_gsi_routes, Jan Kiszka, 2011/10/17