| From 5678de3f15010b9022ee45673f33bcfc71d47b60 Mon Sep 17 00:00:00 2001 |
| From: Paolo Bonzini <pbonzini@redhat.com> |
| Date: Fri, 28 Mar 2014 20:41:50 +0100 |
| Subject: KVM: ioapic: fix assignment of ioapic->rtc_status.pending_eoi (CVE-2014-0155) |
| |
| From: Paolo Bonzini <pbonzini@redhat.com> |
| |
| commit 5678de3f15010b9022ee45673f33bcfc71d47b60 upstream. |
| |
| QE reported that they got the BUG_ON in ioapic_service to trigger. |
| I cannot reproduce it, but there are two reasons why this could happen. |
| |
| The less likely but also easiest one, is when kvm_irq_delivery_to_apic |
| does not deliver to any APIC and returns -1. |
| |
| Because irqe.shorthand == 0, the kvm_for_each_vcpu loop in that |
| function is never reached. However, you can target the similar loop in |
| kvm_irq_delivery_to_apic_fast; just program a zero logical destination |
| address into the IOAPIC, or an out-of-range physical destination address. |
| |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| virt/kvm/ioapic.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/virt/kvm/ioapic.c |
| +++ b/virt/kvm/ioapic.c |
| @@ -306,7 +306,7 @@ static int ioapic_deliver(struct kvm_ioa |
| BUG_ON(ioapic->rtc_status.pending_eoi != 0); |
| ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, |
| ioapic->rtc_status.dest_map); |
| - ioapic->rtc_status.pending_eoi = ret; |
| + ioapic->rtc_status.pending_eoi = (ret < 0 ? 0 : ret); |
| } else |
| ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL); |
| |
