From patchwork Fri Feb 21 12:48:49 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 322710 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 8CDD12C0236 for ; Fri, 21 Feb 2014 23:53:51 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1WGpbw-00029t-85; Fri, 21 Feb 2014 12:53:48 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1WGpZo-0001DF-0a for kernel-team@lists.ubuntu.com; Fri, 21 Feb 2014 12:51:36 +0000 Received: from bl20-128-115.dsl.telepac.pt ([2.81.128.115] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1WGpZn-00029c-Pb; Fri, 21 Feb 2014 12:51:35 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com 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 Cc: "H. Peter Anvin" X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 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);