When kvm_irq_delivery_to_apic_fast() is called with APIC_DEST_SELF
shorthand, 'src' must not be NULL. Crash the VM with KVM_BUG_ON()
instead of crashing the host.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/lapic.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 80a2020c4db4..66b0eb0bda94 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1024,6 +1024,10 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 	*r = -1;
 
 	if (irq->shorthand == APIC_DEST_SELF) {
+		if (KVM_BUG_ON(!src, kvm)) {
+			*r = 0;
+			return true;
+		}
 		*r = kvm_apic_set_irq(src->vcpu, irq, dest_map);
 		return true;
 	}
-- 
2.35.1