[PATCH 4.14 031/165] KVM: vmx: use local variable for current_vmptr when emulating VMPTRST

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sean Christopherson <sean.j.christopher...@intel.com>

[ Upstream commit 0a06d4256674c4e041945b52044941995fee237d ]

Do not expose the address of vmx->nested.current_vmptr to
kvm_write_guest_virt_system() as the resulting __copy_to_user()
call will trigger a WARN when CONFIG_HARDENED_USERCOPY is
enabled.

Opportunistically clean up variable names in handle_vmptrst()
to improve readability, e.g. vmcs_gva is misleading as the
memory operand of VMPTRST is plain memory, not a VMCS.

Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com>
Tested-by: Peter Shier <psh...@google.com>
Reviewed-by: Peter Shier <psh...@google.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 arch/x86/kvm/vmx.c |   15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8108,21 +8108,20 @@ static int handle_vmptrld(struct kvm_vcp
 /* Emulate the VMPTRST instruction */
 static int handle_vmptrst(struct kvm_vcpu *vcpu)
 {
-       unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
-       u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
-       gva_t vmcs_gva;
+       unsigned long exit_qual = vmcs_readl(EXIT_QUALIFICATION);
+       u32 instr_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+       gpa_t current_vmptr = to_vmx(vcpu)->nested.current_vmptr;
        struct x86_exception e;
+       gva_t gva;
 
        if (!nested_vmx_check_permission(vcpu))
                return 1;
 
-       if (get_vmx_mem_address(vcpu, exit_qualification,
-                       vmx_instruction_info, true, &vmcs_gva))
+       if (get_vmx_mem_address(vcpu, exit_qual, instr_info, true, &gva))
                return 1;
        /* *_system ok, nested_vmx_check_permission has verified cpl=0 */
-       if (kvm_write_guest_virt_system(vcpu, vmcs_gva,
-                                       (void 
*)&to_vmx(vcpu)->nested.current_vmptr,
-                                       sizeof(u64), &e)) {
+       if (kvm_write_guest_virt_system(vcpu, gva, (void *)&current_vmptr,
+                                       sizeof(gpa_t), &e)) {
                kvm_inject_page_fault(vcpu, &e);
                return 1;
        }