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Commit 3d4213fa authored by Jan H. Schönherr's avatar Jan H. Schönherr Committed by Greg Kroah-Hartman
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KVM: VMX: Do not BUG() on out-of-bounds guest IRQ 



commit 3a8b0677fc6180a467e26cc32ce6b0c09a32f9bb upstream.

The value of the guest_irq argument to vmx_update_pi_irte() is
ultimately coming from a KVM_IRQFD API call. Do not BUG() in
vmx_update_pi_irte() if the value is out-of bounds. (Especially,
since KVM as a whole seems to hang after that.)

Instead, print a message only once if we find that we don't have a
route for a certain IRQ (which can be out-of-bounds or within the
array).

This fixes CVE-2017-1000252.

Fixes: efc64404 ("KVM: x86: Update IRTE for posted-interrupts")
Signed-off-by: default avatarJan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e3a643b3

arch/x86/kvm/vmx.c

+7 −2
Original line number Diff line number Diff line
@@ -11153,7 +11153,7 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq, 
	struct kvm_lapic_irq irq;

	struct kvm_vcpu *vcpu;

	struct vcpu_data vcpu_info;

	int idx, ret = -EINVAL;

	int idx, ret = 0;



	if (!kvm_arch_has_assigned_device(kvm) ||

		!irq_remapping_cap(IRQ_POSTING_CAP) ||
@@ -11162,7 +11162,12 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq, 


	idx = srcu_read_lock(&kvm->irq_srcu);

	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);

	BUG_ON(guest_irq >= irq_rt->nr_rt_entries);

	if (guest_irq >= irq_rt->nr_rt_entries ||

	    hlist_empty(&irq_rt->map[guest_irq])) {

		pr_warn_once("no route for guest_irq %u/%u (broken user space?)\n",

			     guest_irq, irq_rt->nr_rt_entries);

		goto out;

	}



	hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {

		if (e->type != KVM_IRQ_ROUTING_MSI)