39 lines
1.4 KiB
Diff
39 lines
1.4 KiB
Diff
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Bugzilla: 1085016
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Upstream-status: Queued for 3.15
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From 5678de3f15010b9022ee45673f33bcfc71d47b60 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Fri, 28 Mar 2014 20:41:50 +0100
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Subject: KVM: ioapic: fix assignment of ioapic->rtc_status.pending_eoi
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(CVE-2014-0155)
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QE reported that they got the BUG_ON in ioapic_service to trigger.
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I cannot reproduce it, but there are two reasons why this could happen.
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The less likely but also easiest one, is when kvm_irq_delivery_to_apic
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does not deliver to any APIC and returns -1.
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Because irqe.shorthand == 0, the kvm_for_each_vcpu loop in that
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function is never reached. However, you can target the similar loop in
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kvm_irq_delivery_to_apic_fast; just program a zero logical destination
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address into the IOAPIC, or an out-of-range physical destination address.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
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index d4b6015..d98d107 100644
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--- a/virt/kvm/ioapic.c
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+++ b/virt/kvm/ioapic.c
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@@ -356,7 +356,7 @@ static int ioapic_service(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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--
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cgit v0.10.1
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