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authorJim Mattson <jmattson@google.com>2017-09-12 13:02:54 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-05 09:47:33 +0200
commit27920625f93e59b2b24bdadf946ae4b61f885f40 (patch)
treedd9965e8d7f2aacf925f8403d448271a96b8c18f
parentc69768cc3eb4fb41a0f3c47c6d6575fd8ead57b7 (diff)
kvm: nVMX: Don't allow L2 to access the hardware CR8
commit 51aa68e7d57e3217192d88ce90fd5b8ef29ec94f upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/vmx.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1917af45605f..1b8b1a1bf7e9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10271,6 +10271,11 @@ 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
}
/*