KVM: check injected pic irq within valid pic irqs

Check that an injected pic irq is between 0 and 15.

Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 5857f59..c31164e 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -130,8 +130,10 @@
 {
 	struct kvm_pic *s = opaque;
 
-	pic_set_irq1(&s->pics[irq >> 3], irq & 7, level);
-	pic_update_irq(s);
+	if (irq >= 0 && irq < PIC_NUM_PINS) {
+		pic_set_irq1(&s->pics[irq >> 3], irq & 7, level);
+		pic_update_irq(s);
+	}
 }
 
 /*
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 2a15be2..7ca47cb 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -30,6 +30,8 @@
 #include "ioapic.h"
 #include "lapic.h"
 
+#define PIC_NUM_PINS 16
+
 struct kvm;
 struct kvm_vcpu;