Patch "kvm: nVMX: Don't allow L2 to access the hardware CR8" has been added to the 4.13-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    kvm: nVMX: Don't allow L2 to access the hardware CR8

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-nvmx-don-t-allow-l2-to-access-the-hardware-cr8.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 51aa68e7d57e3217192d88ce90fd5b8ef29ec94f Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@google.com>
Date: Tue, 12 Sep 2017 13:02:54 -0700
Subject: kvm: nVMX: Don't allow L2 to access the hardware CR8

From: Jim Mattson <jmattson@google.com>

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>

---
 arch/x86/kvm/vmx.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10271,6 +10271,11 @@ static int prepare_vmcs02(struct kvm_vcp
 	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
 	}
 
 	/*


Patches currently in stable-queue which might be from jmattson@google.com are

queue-4.13/kvm-nvmx-don-t-allow-l2-to-access-the-hardware-cr8.patch