CVE request -- kernel: kvm: device assignment DoS

[Petr Matousek <pmatouse () redhat com>]

It was found that kvm_vm_ioctl_assign_device function did not check if
the user requesting assignment was privileged or not. Together with
/dev/kvm being 666, unprivileged user could assign unused pci devices,
or even devices that were in use and whose resources were not properly
claimed by the respective drivers.

Please note that privileged access was still needed to re-program the
device to for example issue DMA requests. This is typically achieved by
touching files on sysfs filesystem. These files are usually not
accessible to unprivileged users.

As a result, local user could use this flaw to crash the system.

Reference:
https://bugzilla.redhat.com/show_bug.cgi?id=756084
http://thread.gmane.org/gmane.comp.emulators.kvm.devel/82043

Thanks,
-- 
Petr Matousek / Red Hat Security Response Team