Fix limit checking for all segment types except expand-down data segments.
The effective limit is the last address that is allowed to be accessed in the
segment. The condition for exceeding the limit should be
offset + operand_size - 1 > limit
For example, if offset == limit and operand size is one, there is no limit
exceeding (limit + 1 - 1 == limit), but if operand size is two, the limit
is exceeded (limit + 2 - 1 > limit).
Signed-off-by: Eugene Korenevsky <ekorenevsky@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 32d2979..faa05a4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6377,7 +6377,7 @@ static int vmx_protmode_seg_check(struct kvm_vcpu *vcpu,
/* #GP(0)/#SS(0) if the segment is unusable. */
exn = (s->unusable != 0);
/* #GP(0)/#SS(0) if the memory operand is outside the segment limit. */
- exn = exn || (off + mem_op_size > s->limit);
+ exn = exn || (off + mem_op_size - 1 > s->limit);
if (exn) {
kvm_queue_exception_e(vcpu,
seg == VCPU_SREG_SS ?
--
2.1.4
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