From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755598AbaIKMgP (ORCPT ); Thu, 11 Sep 2014 08:36:15 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51708 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755478AbaIKMeJ (ORCPT ); Thu, 11 Sep 2014 08:34:09 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Nadav Amit" , "Paolo Bonzini" Date: Thu, 11 Sep 2014 13:32:13 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 001/131] KVM: x86: Inter-privilege level ret emulation is not implemeneted In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Nadav Amit commit 9e8919ae793f4edfaa29694a70f71a515ae9942a upstream. 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. Signed-off-by: Nadav Amit Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- arch/x86/kvm/emulate.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1818,6 +1818,7 @@ static int em_ret_far(struct x86_emulate { int rc; unsigned long cs; + int cpl = ctxt->ops->cpl(ctxt); rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes); if (rc != X86EMUL_CONTINUE) @@ -1827,6 +1828,9 @@ static int em_ret_far(struct x86_emulate 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; }