Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932890AbaBUM5x (ORCPT ); Fri, 21 Feb 2014 07:57:53 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47259 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932599AbaBUMvg (ORCPT ); Fri, 21 Feb 2014 07:51:36 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: "H. Peter Anvin" , Luis Henriques Subject: [PATCH 3.11 105/121] x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off Date: Fri, 21 Feb 2014 12:48:49 +0000 Message-Id: <1392986945-9693-106-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1392986945-9693-1-git-send-email-luis.henriques@canonical.com> References: <1392986945-9693-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: "H. Peter Anvin" commit 4640c7ee9b8953237d05a61ea3ea93981d1bc961 upstream. If CONFIG_X86_SMAP is disabled, smap_violation() tests for conditions which are incorrect (as the AC flag doesn't matter), causing spurious faults. The dynamic disabling of SMAP (nosmap on the command line) is fine because it disables X86_FEATURE_SMAP, therefore causing the static_cpu_has() to return false. Found by Fengguang Wu's test system. [ v3: move all predicates into smap_violation() ] [ v2: use IS_ENABLED() instead of #ifdef ] Reported-by: Fengguang Wu Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost Signed-off-by: H. Peter Anvin Signed-off-by: Luis Henriques --- arch/x86/mm/fault.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 654be4a..c1e9e4c 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -989,6 +989,12 @@ static int fault_in_kernel_space(unsigned long address) static inline bool smap_violation(int error_code, struct pt_regs *regs) { + if (!IS_ENABLED(CONFIG_X86_SMAP)) + return false; + + if (!static_cpu_has(X86_FEATURE_SMAP)) + return false; + if (error_code & PF_USER) return false; @@ -1091,11 +1097,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) if (unlikely(error_code & PF_RSVD)) pgtable_bad(regs, error_code, address); - if (static_cpu_has(X86_FEATURE_SMAP)) { - if (unlikely(smap_violation(error_code, regs))) { - bad_area_nosemaphore(regs, error_code, address); - return; - } + if (unlikely(smap_violation(error_code, regs))) { + bad_area_nosemaphore(regs, error_code, address); + return; } perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/