[Bug 43339] New: Wrong Pci-Bridge Header Type check.

[Bug 43339] New: Wrong Pci-Bridge Header Type check.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=43339

           Summary: Wrong Pci-Bridge Header Type check.
           Product: Virtualization
           Version: unspecified
    Kernel Version: 3.4
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
        AssignedTo: virtualization_kvm@kernel-bugs.osdl.org
        ReportedBy: vedun@ispras.ru
        Regression: No


I have found bug in file virt/kvm/assigned-device.c

670         /* Don't allow bridges to be assigned */
671         pci_read_config_byte(dev, PCI_HEADER_TYPE, &header_type);
672         if ((header_type & PCI_HEADER_TYPE) != PCI_HEADER_TYPE_NORMAL) {
673                 r = -EPERM;
674                 goto out_put;
675         }

This code doesn't check that device is PCI-Bridge. In my case

header_type is 1,  default value for PCI-Bridge
PCI_HEADER_TYPE is 14(0xE)
PCI_HEADER_TYPE_NORMAL is 0

So, 1 & 0xE == 0 thus KVM assigns pci-bridge device to VM successfully.

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[Bug 43339] Wrong Pci-Bridge Header Type check.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=43339


Alex Williamson <alex.williamson@redhat.com> changed:

           What    |Removed                     |Added
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                 CC|                            |alex.williamson@redhat.com




--- Comment #1 from Alex Williamson <alex.williamson@redhat.com>  2012-06-05 18:33:46 ---
(In reply to comment #0)
> 
> So, 1 & 0xE == 0 thus KVM assigns pci-bridge device to VM successfully.

Have you found this to be true in practice?  The test here is clearly wrong,
but immediately after this we test pci-sysfs resource permissions.  We only
test standard device resources, as we're not expecting a bridge to get through,
but I believe those should all be zero for a bridge, which will result in
denying assignment of the device because it has no resources.  If you have a
pci-bridge that actually makes it through that test, please include lspci -vvv
for it here.  Thanks

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[Bug 43339] Wrong Pci-Bridge Header Type check.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=43339





--- Comment #2 from Alex Williamson <alex.williamson@redhat.com>  2012-06-05 19:43:18 ---
Follow-up; I guess a bridge implementing BARs is not that unique.  Many bridges
do not have BARs, which should be rejected from assignment outright.  Those
with BARs will still fall into the requirement that the user will require
permission to the pci-sysfs resource files, so a privileged entity still has to
grant access to the device.  Let me know if you find differently.  Thanks

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[Bug 43339] Wrong Pci-Bridge Header Type check.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=43339


Florian Mickler <florian@mickler.org> changed:

           What    |Removed                     |Added
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                 CC|                            |florian@mickler.org




--- Comment #3 from Florian Mickler <florian@mickler.org>  2012-07-01 09:40:03 ---
A patch referencing this bug report has been merged in Linux v3.5-rc4:

commit f961f72836eb6c0fd76201f6f6b2fafff93c4cea
Author: Jan Kiszka <jan.kiszka@siemens.com>
Date:   Fri Jun 15 07:56:20 2012 -0600

    KVM: Fix PCI header check on device assignment

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[Bug 43339] Wrong Pci-Bridge Header Type check.

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=43339


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |alan@lxorguk.ukuu.org.uk
         Resolution|                            |CODE_FIX




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