KVM: x86 emulator: refuse SrcMemFAddr (e.g. LDS) with register operand

SrcMemFAddr is not defined with the modrm operand designating a register
instead of a memory address.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ec35a71d8b5d..2b9b0feabdba 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2974,6 +2974,11 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
                 goto done;
         }
 
+        if ((c->d & SrcMask) == SrcMemFAddr && c->src.type != OP_MEM) {
+                emulate_ud(ctxt);
+                goto done;
+        }
+
         /* Privileged instruction can be executed only in CPL=0 */
         if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) {
                 emulate_gp(ctxt, 0);