From patchwork Wed Mar 2 14:26:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 63386 Delivered-To: patch@linaro.org Received: by 10.112.199.169 with SMTP id jl9csp2413039lbc; Wed, 2 Mar 2016 06:27:00 -0800 (PST) X-Received: by 10.66.145.194 with SMTP id sw2mr38375735pab.69.1456928819050; Wed, 02 Mar 2016 06:26:59 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id i62si2506136pfi.222.2016.03.02.06.26.58; Wed, 02 Mar 2016 06:26:59 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754161AbcCBO0p (ORCPT + 30 others); Wed, 2 Mar 2016 09:26:45 -0500 Received: from foss.arm.com ([217.140.101.70]:58793 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751582AbcCBO0n (ORCPT ); Wed, 2 Mar 2016 09:26:43 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 498DF520; Wed, 2 Mar 2016 06:25:47 -0800 (PST) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DD7353F213; Wed, 2 Mar 2016 06:26:40 -0800 (PST) From: Mark Rutland To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: akpm@linux-foundation.org, aryabinin@virtuozzo.com, catalin.marinas@arm.com, glider@google.com, lorenzo.pieralisi@arm.com, mark.rutland@arm.com, mingo@redhat.com, peterz@infradead.org, will.deacon@arm.com Subject: [PATCH 2/3] sched/kasan: remove stale KASAN poison after hotplug Date: Wed, 2 Mar 2016 14:26:17 +0000 Message-Id: <1456928778-22491-3-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1456928778-22491-1-git-send-email-mark.rutland@arm.com> References: <1456928778-22491-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Functions which the compiler has instrumented for ASAN place poison on the stack shadow upon entry and remove this poison prior to returning. In the case of CPU hotplug, CPUs exit the kernel a number of levels deep in C code. Any instrumented functions on this critical path will leave portions of the stack shadow poisoned. When a CPU is subsequently brought back into the kernel via a different path, depending on stackframe, layout calls to instrumented functions may hit this stale poison, resulting in (spurious) KASAN splats to the console. To avoid this, clear any stale poison from the idle thread for a CPU prior to bringing a CPU online. Signed-off-by: Mark Rutland Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Ingo Molnar Cc: Lorenzo Pieralisi Cc: Peter Zijlstra Cc: Will Deacon --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) -- 1.9.1 diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9503d59..41f6b22 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -26,6 +26,7 @@ * Thomas Gleixner, Mike Kravetz */ +#include #include #include #include @@ -5096,6 +5097,8 @@ void init_idle(struct task_struct *idle, int cpu) idle->state = TASK_RUNNING; idle->se.exec_start = sched_clock(); + kasan_unpoison_task_stack(idle); + #ifdef CONFIG_SMP /* * Its possible that init_idle() gets called multiple times on a task,