From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 25 Mar 2022 13:21:39 +0000 (+0100)
Subject: KVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()
X-Git-Tag: v5.16.19~117
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e38128f8bd1d4f2244d8a393bc5dc204a99a541;p=thirdparty%2Fkernel%2Fstable.git

KVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()

commit 00b5f37189d24ac3ed46cb7f11742094778c46ce upstream.

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>
Message-Id: <20220325132140.25650-3-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6c87032c928cb..5c7a033d39d13 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -987,6 +987,10 @@ 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;
 	}