KVM: properly check max PIC pin in irq route setup

Otherwise memory beyond irq_states[16] might be accessed.

Noticed by Juan Quintela.

Cc: stable@kernel.org
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 9b077342ab54..9fd5b3ebc517 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -302,6 +302,7 @@ static int setup_routing_entry(struct kvm_irq_routing_table *rt,
 {
         int r = -EINVAL;
         int delta;
+        unsigned max_pin;
         struct kvm_kernel_irq_routing_entry *ei;
         struct hlist_node *n;
 
@@ -322,12 +323,15 @@ static int setup_routing_entry(struct kvm_irq_routing_table *rt,
                 switch (ue->u.irqchip.irqchip) {
                 case KVM_IRQCHIP_PIC_MASTER:
                         e->set = kvm_set_pic_irq;
+                        max_pin = 16;
                         break;
                 case KVM_IRQCHIP_PIC_SLAVE:
                         e->set = kvm_set_pic_irq;
+                        max_pin = 16;
                         delta = 8;
                         break;
                 case KVM_IRQCHIP_IOAPIC:
+                        max_pin = KVM_IOAPIC_NUM_PINS;
                         e->set = kvm_set_ioapic_irq;
                         break;
                 default:
@@ -335,7 +339,7 @@ static int setup_routing_entry(struct kvm_irq_routing_table *rt,
                 }
                 e->irqchip.irqchip = ue->u.irqchip.irqchip;
                 e->irqchip.pin = ue->u.irqchip.pin + delta;
-                if (e->irqchip.pin >= KVM_IOAPIC_NUM_PINS)
+                if (e->irqchip.pin >= max_pin)
                         goto out;
                 rt->chip[ue->u.irqchip.irqchip][e->irqchip.pin] = ue->gsi;
                 break;