[PATCH AUTOSEL 5.1 057/141] kvm: vmx: segment limit check: use access length

Sasha Levin
2019-07-19T04:31:20Z

From: Eugene Korenevsky <ekorenevsky@gmail.com>

[ Upstream commit fdb28619a8f033c13f5d9b9e8b5536bb6e68a2c3 ]

There is an imperfection in get_vmx_mem_address(): access length is ignored
when checking the limit. To fix this, pass access length as a function argument.
The access length is usually obvious since it is used by callers after
get_vmx_mem_address() call, but for vmread/vmwrite it depends on the
state of 64-bit mode.

Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/vmx/nested.c | 28 ++++++++++++++++------------
arch/x86/kvm/vmx/nested.h | 2 +-
arch/x86/kvm/vmx/vmx.c | 3 ++-
3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 79c76318bcb8..0d92cac9ed17 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4040,7 +4040,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
* #UD or #GP.
*/
int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
- u32 vmx_instruction_info, bool wr, gva_t *ret)
+ u32 vmx_instruction_info, bool wr, int len, gva_t *ret)
{
gva_t off;
bool exn;
@@ -4147,7 +4147,7 @@ int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
*/
if (!(s.base == 0 && s.limit == 0xffffffff &&
((s.type & 8) || !(s.type & 4))))
- exn = exn || ((u64)off + sizeof(u64) - 1 > s.limit);
+ exn = exn || ((u64)off + len - 1 > s.limit);
}
if (exn) {
kvm_queue_exception_e(vcpu,
@@ -4166,7 +4166,8 @@ static int nested_vmx_get_vmptr(struct kvm_vcpu *vcpu, gpa_t *vmpointer)
struct x86_exception e;

if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION),
- vmcs_read32(VMX_INSTRUCTION_INFO), false, &gva))
+ vmcs_read32(VMX_INSTRUCTION_INFO), false,
+ sizeof(*vmpointer), &gva))
return 1;

if (kvm_read_guest_virt(vcpu, gva, vmpointer, sizeof(*vmpointer), &e)) {
@@ -4426,6 +4427,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
u64 field_value;
unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+ int len;
gva_t gva = 0;
struct vmcs12 *vmcs12;

@@ -4463,12 +4465,12 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
kvm_register_writel(vcpu, (((vmx_instruction_info) >> 3) & 0xf),
field_value);
} else {
+ len = is_64_bit_mode(vcpu) ? 8 : 4;
if (get_vmx_mem_address(vcpu, exit_qualification,
- vmx_instruction_info, true, &gva))
+ vmx_instruction_info, true, len, &gva))
return 1;
/* _system ok, nested_vmx_check_permission has verified cpl=0 */
- kvm_write_guest_virt_system(vcpu, gva, &field_value,
- (is_long_mode(vcpu) ? 8 : 4), NULL);
+ kvm_write_guest_virt_system(vcpu, gva, &field_value, len, NULL);
}

return nested_vmx_succeed(vcpu);
@@ -4478,6 +4480,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
static int handle_vmwrite(struct kvm_vcpu *vcpu)
{
unsigned long field;
+ int len;
gva_t gva;
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
@@ -4503,11 +4506,11 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
field_value = kvm_register_readl(vcpu,
(((vmx_instruction_info) >> 3) & 0xf));
else {
+ len = is_64_bit_mode(vcpu) ? 8 : 4;
if (get_vmx_mem_address(vcpu, exit_qualification,
- vmx_instruction_info, false, &gva))
+ vmx_instruction_info, false, len, &gva))
return 1;
- if (kvm_read_guest_virt(vcpu, gva, &field_value,
- (is_64_bit_mode(vcpu) ? 8 : 4), &e)) {
+ if (kvm_read_guest_virt(vcpu, gva, &field_value, len, &e)) {
kvm_inject_page_fault(vcpu, &e);
return 1;
}
@@ -4667,7 +4670,8 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu)
if (unlikely(to_vmx(vcpu)->nested.hv_evmcs))
return 1;

- if (get_vmx_mem_address(vcpu, exit_qual, instr_info, true, &gva))
+ if (get_vmx_mem_address(vcpu, exit_qual, instr_info,
+ true, sizeof(gpa_t), &gva))
return 1;
/* *_system ok, nested_vmx_check_permission has verified cpl=0 */
if (kvm_write_guest_virt_system(vcpu, gva, (void *)&current_vmptr,
@@ -4713,7 +4717,7 @@ static int handle_invept(struct kvm_vcpu *vcpu)
* operand is read even if it isn't needed (e.g., for type==global)
*/
if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION),
- vmx_instruction_info, false, &gva))
+ vmx_instruction_info, false, sizeof(operand), &gva))
return 1;
if (kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e)) {
kvm_inject_page_fault(vcpu, &e);
@@ -4775,7 +4779,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
* operand is read even if it isn't needed (e.g., for type==global)
*/
if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION),
- vmx_instruction_info, false, &gva))
+ vmx_instruction_info, false, sizeof(operand), &gva))
return 1;
if (kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e)) {
kvm_inject_page_fault(vcpu, &e);
diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index e847ff1019a2..29d205bb4e4f 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -21,7 +21,7 @@ void nested_sync_from_vmcs12(struct kvm_vcpu *vcpu);
int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
int vmx_get_vmx_msr(struct nested_vmx_msrs *msrs, u32 msr_index, u64 *pdata);
int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
- u32 vmx_instruction_info, bool wr, gva_t *ret);
+ u32 vmx_instruction_info, bool wr, int len, gva_t *ret);

static inline struct vmcs12 *get_vmcs12(struct kvm_vcpu *vcpu)
{
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cfb8f1ec9a0a..b2cb35e0c24a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5343,7 +5343,8 @@ static int handle_invpcid(struct kvm_vcpu *vcpu)
* is read even if it isn't needed (e.g., for type==all)
*/
if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION),
- vmx_instruction_info, false, &gva))
+ vmx_instruction_info, false,
+ sizeof(operand), &gva))
return 1;

if (kvm_read_guest_virt(vcpu, gva, &operand, sizeof(operand), &e)) {
--
2.20.1