The create_pit_timer function in arch/x86/kvm/i8254.c in KVM 83, and possibly other versions, does not properly handle when Programmable Interval Timer (PIT) interrupt requests (IRQs) when a virtual interrupt controller (irqchip) is not available, which allows local users to cause a denial of service (NULL pointer dereference) by starting a timer.
lists.opensuse.org/opensuse-security-announce/2012-05/msg00013.html
lists.opensuse.org/opensuse-security-announce/2013-06/msg00005.html
permalink.gmane.org/gmane.comp.emulators.kvm.devel/83564
www.openwall.com/lists/oss-security/2011/12/21/7
www.redhat.com/support/errata/RHSA-2012-0051.html
www.securityfocus.com/bid/51172
www.securitytracker.com/id?1026559
bugzilla.redhat.com/show_bug.cgi?id=769721