From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752923AbcBLSum (ORCPT ); Fri, 12 Feb 2016 13:50:42 -0500 Received: from mail-pf0-f182.google.com ([209.85.192.182]:34914 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752589AbcBLSui (ORCPT ); Fri, 12 Feb 2016 13:50:38 -0500 Subject: Re: [PATCH] trace, kasan: silence Kasan warning in check_stack To: Andrey Ryabinin , rostedt@goodmis.org, mingo@redhat.com References: <1454956782-5944-1-git-send-email-yang.shi@linaro.org> <56B9EC3C.4040405@virtuozzo.com> Cc: linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org From: "Shi, Yang" Message-ID: <56BE297C.2060402@linaro.org> Date: Fri, 12 Feb 2016 10:50:36 -0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56B9EC3C.4040405@virtuozzo.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steven, Any comment for this patch? Thanks, Yang On 2/9/2016 5:40 AM, Andrey Ryabinin wrote: > On 02/08/2016 09:39 PM, Yang Shi wrote: >> When enabling stack trace via "echo 1 > /proc/sys/kernel/stack_tracer_enabled", >> the below KASAN warning is triggered: >> >> BUG: KASAN: stack-out-of-bounds in check_stack+0x344/0x848 at addr ffffffc0689ebab8 >> Read of size 8 by task ksoftirqd/4/29 >> page:ffffffbdc3a27ac0 count:0 mapcount:0 mapping: (null) index:0x0 >> flags: 0x0() >> page dumped because: kasan: bad access detected >> CPU: 4 PID: 29 Comm: ksoftirqd/4 Not tainted 4.5.0-rc1 #129 >> Hardware name: Freescale Layerscape 2085a RDB Board (DT) >> Call trace: >> [] dump_backtrace+0x0/0x3a0 >> [] show_stack+0x24/0x30 >> [] dump_stack+0xd8/0x168 >> [] kasan_report_error+0x6a0/0x920 >> [] kasan_report+0x70/0xb8 >> [] __asan_load8+0x60/0x78 >> [] check_stack+0x344/0x848 >> [] stack_trace_call+0x1c4/0x370 >> [] ftrace_ops_no_ops+0x2c0/0x590 >> [] ftrace_graph_call+0x0/0x14 >> [] fpsimd_thread_switch+0x24/0x1e8 >> [] __switch_to+0x34/0x218 >> [] __schedule+0x3ac/0x15b8 >> [] schedule+0x5c/0x178 >> [] smpboot_thread_fn+0x350/0x960 >> [] kthread+0x1d8/0x2b0 >> [] ret_from_fork+0x10/0x40 >> Memory state around the buggy address: >> ffffffc0689eb980: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f4 f4 f4 >> ffffffc0689eba00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffffffc0689eba80: 00 00 f1 f1 f1 f1 00 f4 f4 f4 f3 f3 f3 f3 00 00 >> ^ >> ffffffc0689ebb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffffffc0689ebb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> >> The stacker tracer traverses the whole kernel stack when saving the max stack >> trace. It may touch the stack red zones to cause the warning. So, just disable >> the instrumentation to silence the warning. >> >> Signed-off-by: Yang Shi > > Acked-by: Andrey Ryabinin >