[PATCH 4.14 168/229] KVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()

Greg Kroah-Hartman
2022-08-23T10:10:05Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

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: Stefan Ghinea <stefan.ghinea@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/lapic.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -894,6 +894,10 @@ bool kvm_irq_delivery_to_apic_fast(struc
*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;
}