From: Vitaly Kuznetsov Date: Fri, 25 Mar 2022 13:21:38 +0000 (+0100) Subject: KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq X-Git-Tag: v5.16.19~118 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6e3cd49aed556ea1784558001aee7c156a93cbc4;p=thirdparty%2Fkernel%2Fstable.git KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq commit 7ec37d1cbe17d8189d9562178d8b29167fe1c31a 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 Message-Id: <20220325132140.25650-2-vkuznets@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index edf024f1f1418..69952d957887b 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -446,6 +446,9 @@ 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;