kvm: nVMX: Don't allow L2 to access the hardware CR8
If L1 does not specify the "use TPR shadow" VM-execution control in vmcs12, then L0 must specify the "CR8-load exiting" and "CR8-store exiting" VM-execution controls in vmcs02. Failure to do so will give the L2 VM unrestricted read/write access to the hardware CR8. This fixes CVE-2017-12154. Signed-off-by: Jim Mattson <jmattson@google.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -10525,6 +10525,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
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if (exec_control & CPU_BASED_TPR_SHADOW) {
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vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, -1ull);
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vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold);
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} else {
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#ifdef CONFIG_X86_64
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exec_control |= CPU_BASED_CR8_LOAD_EXITING |
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CPU_BASED_CR8_STORE_EXITING;
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#endif
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}
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/*
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