KVM: Fix buffer overflow in kvm_set_irq()

Bugdb: 13966
kvm_set_irq() has an internal buffer of three irq routing entries, allowing
connecting a GSI to three IRQ chips or on MSI.  However setup_routing_entry()
does not properly enforce this, allowing three irqchip routes followed by
an MSI route to overflow the buffer.

Fix by ensuring that an MSI entry is added to an empty list.
This fixes: CVE-2012-2137
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 9f614b4e365f77e38ce4b8dec4eeac15148cd5b7..272407c00ede79ed68a8909f484ed19c0cdb340d 100644 (file)
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -318,6 +318,7 @@ static int setup_routing_entry(struct kvm_irq_routing_table *rt,
         */
        hlist_for_each_entry(ei, n, &rt->map[ue->gsi], link)
                if (ei->type == KVM_IRQ_ROUTING_MSI ||
+                   ue->type == KVM_IRQ_ROUTING_MSI ||
                    ue->u.irqchip.irqchip == ei->irqchip.irqchip)
                        return r;