From patchwork Mon Oct 27 22:03:43 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nadav Amit X-Patchwork-Id: 5166521 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 951ACC11AC for ; Mon, 27 Oct 2014 22:06:35 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C3C8920166 for ; Mon, 27 Oct 2014 22:06:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3141B200F0 for ; Mon, 27 Oct 2014 22:06:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752562AbaJ0WGa (ORCPT ); Mon, 27 Oct 2014 18:06:30 -0400 Received: from mailgw12.technion.ac.il ([132.68.225.12]:63971 "EHLO mailgw12.technion.ac.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395AbaJ0WG3 (ORCPT ); Mon, 27 Oct 2014 18:06:29 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AmkDAODATlSERCABjGdsb2JhbABchDrVIgKBHBYBARABAQEnQoQDAQUnUhBRVxmIQcYYhWEBAQEBBgIBH5EIBxaENQW4CWqCSwEBAQ X-IPAS-Result: AmkDAODATlSERCABjGdsb2JhbABchDrVIgKBHBYBARABAQEnQoQDAQUnUhBRVxmIQcYYhWEBAQEBBgIBH5EIBxaENQW4CWqCSwEBAQ X-IronPort-AV: E=Sophos;i="5.04,798,1406581200"; d="scan'208";a="126865257" Received: from csa.cs.technion.ac.il ([132.68.32.1]) by mailgw12.technion.ac.il with ESMTP; 28 Oct 2014 00:06:27 +0200 Received: from csn.cs.technion.ac.il (csn.cs.technion.ac.il [132.68.32.15]) by csa.cs.technion.ac.il (Postfix) with ESMTP id 994B9140036; Tue, 28 Oct 2014 00:06:26 +0200 (IST) Received: from csl-tapuz20.cs.technion.ac.il (csl-tapuz20.cs.technion.ac.il [132.68.206.58]) by csn.cs.technion.ac.il (Postfix) with ESMTPSA id 8FCE3A0BAE; Tue, 28 Oct 2014 00:06:26 +0200 (IST) From: Nadav Amit To: pbonzini@redhat.com Cc: dan.carpenter@oracle.com, kvm@vger.kernel.org, Nadav Amit Subject: [PATCH] KVM: x86: Fix far-jump to non-canonical check Date: Tue, 28 Oct 2014 00:03:43 +0200 Message-Id: <1414447423-29298-1-git-send-email-namit@cs.technion.ac.il> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Commit d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far jumps") introduced a bug that caused the fix to be incomplete. Due to incorrect evaluation, far jump to segment with L bit cleared (i.e., 32-bit segment) and RIP with any of the high bits set (i.e, RIP[63:32] != 0) set may not trigger #GP. As we know, this imposes a security problem. In addition, the condition for two warnings was incorrect. Signed-off-by: Nadav Amit Reported-by: Dan Carpenter --- arch/x86/kvm/emulate.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 4b3fa70..a4ee63e 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -577,7 +577,7 @@ static inline int assign_eip_far(struct x86_emulate_ctxt *ctxt, ulong dst, break; case 8: if ((cs_l && is_noncanonical_address(dst)) || - (!cs_l && (dst & ~(u32)-1))) + (!cs_l && (dst >> 32) != 0)) return emulate_gp(ctxt, 0); ctxt->_eip = dst; break; @@ -2016,7 +2016,7 @@ static int em_jmp_far(struct x86_emulate_ctxt *ctxt) rc = assign_eip_far(ctxt, ctxt->src.val, new_desc.l); if (rc != X86EMUL_CONTINUE) { - WARN_ON(!ctxt->mode != X86EMUL_MODE_PROT64); + WARN_ON(ctxt->mode != X86EMUL_MODE_PROT64); /* assigning eip failed; restore the old cs */ ops->set_segment(ctxt, old_sel, &old_desc, 0, VCPU_SREG_CS); return rc; @@ -2104,7 +2104,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) return rc; rc = assign_eip_far(ctxt, eip, new_desc.l); if (rc != X86EMUL_CONTINUE) { - WARN_ON(!ctxt->mode != X86EMUL_MODE_PROT64); + WARN_ON(ctxt->mode != X86EMUL_MODE_PROT64); ops->set_segment(ctxt, old_cs, &old_desc, 0, VCPU_SREG_CS); } return rc;