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KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq

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commit 7ec37d1cbe upstream

When KVM_CAP_HYPERV_SYNIC{,2} is activated, KVM already checks for
irqchip_in_kernel() so normally SynIC irqs should never be set. It is,
however,  possible for a misbehaving VMM to write to SYNIC/STIMER MSRs
causing erroneous behavior.

The immediate issue being fixed is that kvm_irq_delivery_to_apic()
(kvm_irq_delivery_to_apic_fast()) crashes when called with
'irq.shorthand = APIC_DEST_SELF' and 'src == NULL'.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325132140.25650-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vitaly Kuznetsov 2022-08-10 23:24:38 +03:00 • committed by Greg Kroah-Hartman
commit 4c85e207c1
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/hyperv.c
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@ -428,6 +428,9 @@ static int synic_set_irq(struct kvm_vcpu_hv_synic *synic, u32 sint)
struct kvm_lapic_irq irq;
int ret, vector;
if (KVM_BUG_ON(!lapic_in_kernel(vcpu), vcpu->kvm))
return -EINVAL;
if (sint >= ARRAY_SIZE(synic->sint))
return -EINVAL;