diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-07-27 09:00:37 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-07-27 09:04:49 -0400 |
| commit | 0f02bd0ade9a552492463c0159abbe26c4d92b40 (patch) | |
| tree | d9caefa4c391d455f3282981673443684a32c1b2 | |
| parent | 9319676595a2da8022327119e89c8b13f934835e (diff) | |
KVM: nVMX: check for required but missing VMCS12 in KVM_SET_NESTED_STATE
A missing VMCS12 was not causing -EINVAL (it was just read with
copy_from_user, so it is not a security issue, but it is still
wrong). Test for VMCS12 validity and reject the nested state
if a VMCS12 is required but not present.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 13 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/nested.h | 5 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c | 12 |
3 files changed, 26 insertions, 4 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index d4a4cec034d0..6a0e32a7418c 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6108,9 +6108,16 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu, if (ret) return ret; - /* Empty 'VMXON' state is permitted */ - if (kvm_state->size < sizeof(*kvm_state) + sizeof(*vmcs12)) - return 0; + /* Empty 'VMXON' state is permitted if no VMCS loaded */ + if (kvm_state->size < sizeof(*kvm_state) + sizeof(*vmcs12)) { + /* See vmx_has_valid_vmcs12. */ + if ((kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE) || + (kvm_state->flags & KVM_STATE_NESTED_EVMCS) || + (kvm_state->hdr.vmx.vmcs12_pa != -1ull)) + return -EINVAL; + else + return 0; + } if (kvm_state->hdr.vmx.vmcs12_pa != -1ull) { if (kvm_state->hdr.vmx.vmcs12_pa == kvm_state->hdr.vmx.vmxon_pa || diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h index 758bccc26cf9..197148d76b8f 100644 --- a/arch/x86/kvm/vmx/nested.h +++ b/arch/x86/kvm/vmx/nested.h @@ -47,6 +47,11 @@ static inline struct vmcs12 *get_shadow_vmcs12(struct kvm_vcpu *vcpu) return to_vmx(vcpu)->nested.cached_shadow_vmcs12; } +/* + * Note: the same condition is checked against the state provided by userspace + * in vmx_set_nested_state; if it is satisfied, the nested state must include + * the VMCS12. + */ static inline int vmx_has_valid_vmcs12(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); diff --git a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c index d14a34f1b018..94f28a657569 100644 --- a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c +++ b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c @@ -183,9 +183,19 @@ void test_vmx_nested_state(struct kvm_vm *vm) state->hdr.vmx.smm.flags = KVM_STATE_NESTED_SMM_GUEST_MODE; test_nested_state_expect_einval(vm, state); - /* Size must be large enough to fit kvm_nested_state and vmcs12. */ + /* + * Size must be large enough to fit kvm_nested_state and vmcs12 + * if VMCS12 physical address is set + */ + set_default_vmx_state(state, state_sz); + state->size = sizeof(*state); + state->flags = 0; + test_nested_state_expect_einval(vm, state); + set_default_vmx_state(state, state_sz); state->size = sizeof(*state); + state->flags = 0; + state->hdr.vmx.vmcs12_pa = -1; test_nested_state(vm, state); /* |