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KVM: vmx: use local variable for current_vmptr when emulating VMPTRST 

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.christopherson@intel.com>
Tested-by: Peter Shier <pshier@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
zero-colors
Sean Christopherson 2018-07-19 10:31:00 -07:00 committed by Paolo Bonzini
parent 28c20cc73b
commit 0a06d42566
1 changed files with 7 additions and 8 deletions
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15
arch/x86/kvm/vmx.c
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@ -8480,21 +8480,20 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
/* 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;
}