From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760798AbdCVR3E (ORCPT ); Wed, 22 Mar 2017 13:29:04 -0400 Received: from mail-he1eur01on0099.outbound.protection.outlook.com ([104.47.0.99]:52272 "EHLO EUR01-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759459AbdCVR2v (ORCPT ); Wed, 22 Mar 2017 13:28:51 -0400 Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=virtuozzo.com; Subject: Re: [PATCH] kasan: report only the first error To: Andrey Konovalov References: <20170322160647.32032-1-aryabinin@virtuozzo.com> CC: Andrew Morton , Mark Rutland , Alexander Potapenko , "Dmitry Vyukov" , kasan-dev , "Linux Memory Management List" , LKML From: Andrey Ryabinin Message-ID: Date: Wed, 22 Mar 2017 19:54:17 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; 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There are several reasons for this: >> * Single bug quite often has multiple invalid memory accesses causing >> storm in the dmesg. >> * Write OOB access might corrupt metadata so the next report will print >> bogus alloc/free stacktraces. >> * Reports after the first easily could be not bugs by itself but just side >> effects of the first one. >> >> Given that multiple reports only do harm, it makes sense to disable >> kasan after the first one. Except for the tests in lib/test_kasan.c >> as we obviously want to see all reports from test. > > Hi Andrey, > > Could you make it configurable via CONFIG_KASAN_SOMETHING (which can > default to showing only the first report)? I'd rather make this boot time configurable, but wouldn't want to without a good reason. > I sometimes use KASAN to see what bad accesses a particular bug > causes, and seeing all of them (even knowing that they may be > corrupt/induced) helps a lot. I'm wondering why you need to see all reports? > > Thanks! > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 3FB336B0038 for ; Wed, 22 Mar 2017 12:53:02 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id g2so385316938pge.7 for ; Wed, 22 Mar 2017 09:53:02 -0700 (PDT) Received: from EUR03-DB5-obe.outbound.protection.outlook.com (mail-eopbgr40109.outbound.protection.outlook.com. [40.107.4.109]) by mx.google.com with ESMTPS id 31si2441680pli.135.2017.03.22.09.53.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 22 Mar 2017 09:53:01 -0700 (PDT) Subject: Re: [PATCH] kasan: report only the first error References: <20170322160647.32032-1-aryabinin@virtuozzo.com> From: Andrey Ryabinin Message-ID: Date: Wed, 22 Mar 2017 19:54:17 +0300 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Konovalov Cc: Andrew Morton , Mark Rutland , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Linux Memory Management List , LKML On 03/22/2017 07:34 PM, Andrey Konovalov wrote: > On Wed, Mar 22, 2017 at 5:06 PM, Andrey Ryabinin > wrote: >> Disable kasan after the first report. There are several reasons for this: >> * Single bug quite often has multiple invalid memory accesses causing >> storm in the dmesg. >> * Write OOB access might corrupt metadata so the next report will print >> bogus alloc/free stacktraces. >> * Reports after the first easily could be not bugs by itself but just side >> effects of the first one. >> >> Given that multiple reports only do harm, it makes sense to disable >> kasan after the first one. Except for the tests in lib/test_kasan.c >> as we obviously want to see all reports from test. > > Hi Andrey, > > Could you make it configurable via CONFIG_KASAN_SOMETHING (which can > default to showing only the first report)? I'd rather make this boot time configurable, but wouldn't want to without a good reason. > I sometimes use KASAN to see what bad accesses a particular bug > causes, and seeing all of them (even knowing that they may be > corrupt/induced) helps a lot. I'm wondering why you need to see all reports? > > Thanks! > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org