Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758327AbcCCQ5r (ORCPT ); Thu, 3 Mar 2016 11:57:47 -0500 Received: from foss.arm.com ([217.140.101.70]:38499 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932875AbcCCQy4 (ORCPT ); Thu, 3 Mar 2016 11:54:56 -0500 From: Mark Rutland To: linux-mm@kvack.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, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCHv2 2/3] sched/kasan: remove stale KASAN poison after hotplug Date: Thu, 3 Mar 2016 16:54:27 +0000 Message-Id: <1457024068-2236-3-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1457024068-2236-1-git-send-email-mark.rutland@arm.com> References: <1457024068-2236-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1738 Lines: 51 Functions which the compiler has instrumented for ASAN place poison on the stack shadow upon entry and remove this poision 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 Acked-by: Catalin Marinas Reviewed-by: Andrey Ryabinin Reviewed-by: Ingo Molnar Cc: Alexander Potapenko Cc: Andrew Morton Cc: Lorenzo Pieralisi Cc: Peter Zijlstra Cc: Will Deacon --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) 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, -- 1.9.1