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KVM: VMX: Do not BUG() on out-of-bounds guest IRQ

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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: efc644048e ("KVM: x86: Update IRTE for posted-interrupts")
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jan H. Schönherr 2017-09-07 19:02:30 +01:00 committed by Paolo Bonzini
parent 36ae3c0a36
commit 3a8b0677fc
1 changed files with 7 additions and 2 deletions
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9
arch/x86/kvm/vmx.c
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@ -11834,7 +11834,7 @@ 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) ||
@ -11843,7 +11843,12 @@ 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)