From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A32C6C43387 for ; Wed, 16 Jan 2019 16:47:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A64620675 for ; Wed, 16 Jan 2019 16:47:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394263AbfAPQrT (ORCPT ); Wed, 16 Jan 2019 11:47:19 -0500 Received: from foss.arm.com ([217.140.101.70]:52780 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394251AbfAPQrT (ORCPT ); Wed, 16 Jan 2019 11:47:19 -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 06095A78; Wed, 16 Jan 2019 08:47:19 -0800 (PST) Received: from brain-police (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 981C63F5AF; Wed, 16 Jan 2019 08:47:16 -0800 (PST) Date: Wed, 16 Jan 2019 16:47:13 +0000 From: Will Deacon To: Andrey Ryabinin Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Qian Cai , Alexander Potapenko , Dmitry Vyukov , Catalin Marinas Subject: Re: [PATCH] kasan: Remove use after scope bugs detection. Message-ID: <20190116164712.GB1910@brain-police> References: <20190111185842.13978-1-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190111185842.13978-1-aryabinin@virtuozzo.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2019 at 09:58:42PM +0300, Andrey Ryabinin wrote: > Use after scope bugs detector seems to be almost entirely useless > for the linux kernel. It exists over two years, but I've seen only > one valid bug so far [1]. And the bug was fixed before it has been > reported. There were some other use-after-scope reports, but they > were false-positives due to different reasons like incompatibility > with structleak plugin. > > This feature significantly increases stack usage, especially with > GCC < 9 version, and causes a 32K stack overflow. It probably > adds performance penalty too. > > Given all that, let's remove use-after-scope detector entirely. > > While preparing this patch I've noticed that we mistakenly enable > use-after-scope detection for clang compiler regardless of > CONFIG_KASAN_EXTRA setting. This is also fixed now. > > [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com> > > Signed-off-by: Andrey Ryabinin > Cc: Qian Cai > Cc: Alexander Potapenko > Cc: Dmitry Vyukov > Cc: Catalin Marinas > Cc: Will Deacon > --- > arch/arm64/include/asm/memory.h | 4 ---- > lib/Kconfig.debug | 1 - > lib/Kconfig.kasan | 10 ---------- > lib/test_kasan.c | 24 ------------------------ > mm/kasan/generic.c | 19 ------------------- > mm/kasan/generic_report.c | 3 --- > mm/kasan/kasan.h | 3 --- > scripts/Makefile.kasan | 5 ----- > scripts/gcc-plugins/Kconfig | 4 ---- > 9 files changed, 73 deletions(-) For the arm64 part: Acked-by: Will Deacon but I defer to you and Dmitry as to whether or not you go ahead with this. Will