From 51aa68e7d57e3217192d88ce90fd5b8ef29ec94f Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Tue, 12 Sep 2017 13:02:54 -0700 Subject: 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 Reviewed-by: David Hildenbrand Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 09204993a739..8e1ae716f938 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10525,6 +10525,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, if (exec_control & CPU_BASED_TPR_SHADOW) { vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, -1ull); vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold); + } else { +#ifdef CONFIG_X86_64 + exec_control |= CPU_BASED_CR8_LOAD_EXITING | + CPU_BASED_CR8_STORE_EXITING; +#endif } /* -- cgit