From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753498AbbJSIjd (ORCPT ); Mon, 19 Oct 2015 04:39:33 -0400 Received: from mx2.parallels.com ([199.115.105.18]:53964 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752941AbbJSIja (ORCPT ); Mon, 19 Oct 2015 04:39:30 -0400 From: Andrey Ryabinin To: CC: Andrey Ryabinin , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , , Andrew Morton , Andy Lutomirski , Andrey Konovalov , Kostya Serebryany , Alexander Potapenko , kasan-dev , Borislav Petkov , Denys Vlasenko , Andi Kleen , Dmitry Vyukov , Sasha Levin , Wolfram Gloger , "Paul E. McKenney" , Peter Zijlstra Subject: [PATCH v5 2/2] x86/mm: Silence KASAN warnings in get_wchan() Date: Mon, 19 Oct 2015 11:37:18 +0300 Message-ID: <1445243838-17763-3-git-send-email-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.4.9 In-Reply-To: <1445243838-17763-1-git-send-email-aryabinin@virtuozzo.com> References: <1444739750-29241-1-git-send-email-aryabinin@virtuozzo.com> <1445243838-17763-1-git-send-email-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: US-EXCH.sw.swsoft.com (10.255.249.47) To US-EXCH.sw.swsoft.com (10.255.249.47) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_wchan() is racy by design, it may access volatile stack of running task, thus it may access redzone in a stack frame and cause KASAN to warn about this. Use READ_ONCE_NOCHECK() to silence these warnings. Signed-off-by: Andrey Ryabinin Reported-by: Sasha Levin --- arch/x86/kernel/process.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 39e585a..e28db18 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -550,14 +550,14 @@ unsigned long get_wchan(struct task_struct *p) if (sp < bottom || sp > top) return 0; - fp = READ_ONCE(*(unsigned long *)sp); + fp = READ_ONCE_NOCHECK(*(unsigned long *)sp); do { if (fp < bottom || fp > top) return 0; - ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long))); + ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); if (!in_sched_functions(ip)) return ip; - fp = READ_ONCE(*(unsigned long *)fp); + fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); } while (count++ < 16 && p->state != TASK_RUNNING); return 0; } -- 2.4.9