Intel SDM vol. 3, 5.3:
The processor causes a
general-protection exception (or, if the segment is SS, a stack-fault
exception) any time an attempt is made to access the following addresses
in a segment:
- A byte at an offset greater than the effective limit
- A word at an offset greater than the (effective-limit – 1)
- A doubleword at an offset greater than the (effective-limit – 3)
- A quadword at an offset greater than the (effective-limit – 7)
Therefore, the generic limit checking error condition must be
exn = off > limit + 1 - operand_len
but not
exn = off + operand_len > limit
as for now.
Signed-off-by: Eugene Korenevsky <ekorenevsky@xxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f1a69117ac0f..fef3d7031715 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4115,7 +4115,7 @@ 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 || (off + sizeof(u64) > s.limit);
+ exn = exn || (off > s.limit + 1 - sizeof(u64));
}
if (exn) {
kvm_queue_exception_e(vcpu,
--
2.21.0
