[PATCH 3.11 02/70] KVM: ioapic: fix assignment of ioapic->rtc_status.pending_eoi (CVE-2014-0155)

From: Luis Henriques
Date: Wed May 07 2014 - 09:39:59 EST


3.11.10.10 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
virt/kvm/ioapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 2d68297..39dc5bc 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -306,7 +306,7 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
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);

--
1.9.1

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