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Commit 9e8919ae authored by Nadav Amit's avatar Nadav Amit Committed by Paolo Bonzini
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KVM: x86: Inter-privilege level ret emulation is not implemeneted 



Return unhandlable error on inter-privilege level ret instruction.  This is
since the current emulation does not check the privilege level correctly when
loading the CS, and does not pop RSP/SS as needed.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ee212297

arch/x86/kvm/emulate.c

+4 −0
Original line number Diff line number Diff line
@@ -2033,6 +2033,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) 
{

	int rc;

	unsigned long cs;

	int cpl = ctxt->ops->cpl(ctxt);



	rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes);

	if (rc != X86EMUL_CONTINUE)
@@ -2042,6 +2043,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) 
	rc = emulate_pop(ctxt, &cs, ctxt->op_bytes);

	if (rc != X86EMUL_CONTINUE)

		return rc;

	/* Outer-privilege level return is not implemented */

	if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)

		return X86EMUL_UNHANDLEABLE;

	rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS);

	return rc;

}