KVM: ioapic: fix assignment of ioapic->rtc_status.pending_eoi (CVE-2014-0155)
commit 5678de3f15
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>
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@ -306,7 +306,7 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
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BUG_ON(ioapic->rtc_status.pending_eoi != 0);
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ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe,
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ioapic->rtc_status.dest_map);
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ioapic->rtc_status.pending_eoi = ret;
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ioapic->rtc_status.pending_eoi = (ret < 0 ? 0 : ret);
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} else
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ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);
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