Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942089AbcLXBjm (ORCPT ); Fri, 23 Dec 2016 20:39:42 -0500 Received: from mga01.intel.com ([192.55.52.88]:26759 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753510AbcLXBiX (ORCPT ); Fri, 23 Dec 2016 20:38:23 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,396,1477983600"; d="scan'208";a="45999322" From: Ricardo Neri To: Ingo Molnar , Thomas Gleixner , Borislav Petkov , Andy Lutomirski , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, x86@kernel.org, , , Ricardo Neri , Dave Hansen , Adam Buchbinder , Colin Ian King , Lorenzo Stoakes , Qiaowei Ren , "Ravi V . Shankar" Subject: [v2 2/7] x86/mpx: Fail when implicit zero-displacement is used along with R/EBP Date: Fri, 23 Dec 2016 17:37:40 -0800 Message-Id: <20161224013745.108716-3-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20161224013745.108716-1-ricardo.neri-calderon@linux.intel.com> References: <20161224013745.108716-1-ricardo.neri-calderon@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1417 Lines: 40 Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software Developer's Manual volume 2A states that when memory addressing with no explicit displacement (i.e, mod part of ModR/M is 0), a SIB byte is used and the base of the SIB byte points to (R/EBP) (i.e., base = 5), an explicit displacement of 0 must be used. Make the address decoder to return -EINVAL in such a case. Cc: Dave Hansen Cc: Adam Buchbinder Cc: Colin Ian King Cc: Lorenzo Stoakes Cc: Qiaowei Ren Cc: Ravi V. Shankar Cc: x86@kernel.org Signed-off-by: Ricardo Neri --- arch/x86/mm/mpx.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 6a75a75..71681d0 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -120,6 +120,13 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, case REG_TYPE_BASE: regno = X86_SIB_BASE(insn->sib.value); + if (regno == 5 && X86_MODRM_RM(insn->modrm.value) == 0) { + WARN_ONCE(1, "An explicit displacement is required when %sBP used as SIB base.", + (IS_ENABLED(CONFIG_X86_64) && insn->x86_64) ? + "R13 or R" : "E"); + return -EINVAL; + } + if (X86_REX_B(insn->rex_prefix.value)) regno += 8; break; -- 2.9.3