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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no 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 5A447C33CB1 for ; Thu, 16 Jan 2020 06:26:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BE7A2075B for ; Thu, 16 Jan 2020 06:26:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=axtens.net header.i=@axtens.net header.b="oNmexNcV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730635AbgAPG0c (ORCPT ); Thu, 16 Jan 2020 01:26:32 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:40882 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730182AbgAPG0c (ORCPT ); Thu, 16 Jan 2020 01:26:32 -0500 Received: by mail-pl1-f196.google.com with SMTP id s21so7892447plr.7 for ; Wed, 15 Jan 2020 22:26:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=jgsZ87j9zhFzITBOLkD7Zx7YPDB2pB7wEvRvkLTLK58=; b=oNmexNcVAh+3e35uSrHwMbT1gEdNtfFt+AsrrtqPXQmSRoQ2+dPRtMo5LTrIw10hkD u+AKJkLOQ7ejO/lyaa6mLr7Bws1hotDPmNsiYytrmcuCElg5p/2U1uo544G1s8tNj3oi 67cF7zBrygv/ffmERc13Rw9w/bQ1CKyQ31T20= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=jgsZ87j9zhFzITBOLkD7Zx7YPDB2pB7wEvRvkLTLK58=; b=AaJ/MOBDaLbEanEEnXyU3WJK++/UbyJ2rAxMn7ZIxK3MyAU6EYC+ooGvwmdoV7K8Md Ts503PrwenkeDj3WuEHP1DVi9gLUFa0EJ/jiu3Da65dGGOPD69YOBJnazMPATbVMrn06 OsL/DV7l7aUf50YpZzLHi8G7k5GFDBfOfsezaSRt7eiPFeGrrayy9fsRr++v4RvEmJCH vR8lqlOxMc+7Fv/eVc0yiP4nGn3e7WdVcexks+cjeTl3uCW7CvfVfWGzXyuAAq3B6cgt UQSq2agfVW56+0p0nghu0dk25Fsf6WYNknaUnWSyIpHfMkAYkcPAj4b2XknZjW0gPTjc isCg== X-Gm-Message-State: APjAAAUZ4/NpFgQpwB3v1+5IrZj6WabNRCxhtUNe7HaEDVGdMIoAnweS g3hEFxfQLZWeYG59tmnvex/2GHgRTdM= X-Google-Smtp-Source: APXvYqxr6t7CheZI96TYjHdF4c+2lQSa9v9KFUkO88U4heoEGDZYaqbW2enLJb4tzmBEKZ7QkJrRRA== X-Received: by 2002:a17:902:9307:: with SMTP id bc7mr29877693plb.338.1579155990819; Wed, 15 Jan 2020 22:26:30 -0800 (PST) Received: from localhost (2001-44b8-1113-6700-097c-7eed-afd4-cd15.static.ipv6.internode.on.net. [2001:44b8:1113:6700:97c:7eed:afd4:cd15]) by smtp.gmail.com with ESMTPSA id c68sm24184007pfc.156.2020.01.15.22.26.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2020 22:26:30 -0800 (PST) From: Daniel Axtens To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com Cc: linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-xtensa@linux-xtensa.org, x86@kernel.org, dvyukov@google.com, christophe.leroy@c-s.fr, Daniel Axtens Subject: [PATCH v2 0/3] Fix some incompatibilites between KASAN and FORTIFY_SOURCE Date: Thu, 16 Jan 2020 17:26:22 +1100 Message-Id: <20200116062625.32692-1-dja@axtens.net> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3 KASAN self-tests fail on a kernel with both KASAN and FORTIFY_SOURCE: memchr, memcmp and strlen. I have observed this on x86 and powerpc. When FORTIFY_SOURCE is on, a number of functions are replaced with fortified versions, which attempt to check the sizes of the operands. However, these functions often directly invoke __builtin_foo() once they have performed the fortify check. This breaks things in 2 ways: - the three function calls are technically dead code, and can be eliminated. When __builtin_ versions are used, the compiler can detect this. - Using __builtins may bypass KASAN checks if the compiler decides to inline it's own implementation as sequence of instructions, rather than emit a function call that goes out to a KASAN-instrumented implementation. The patches address each reason in turn. Finally, test_memcmp used a stack array without explicit initialisation, which can sometimes break too, so fix that up. v2: - some cleanups, don't mess with arch code as I missed some wrinkles. - add stack array init (patch 3) Daniel Axtens (3): kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE string.h: fix incompatibility between FORTIFY_SOURCE and KASAN kasan: initialise array in kasan_memcmp test include/linux/string.h | 60 +++++++++++++++++++++++++++++++++--------- lib/test_kasan.c | 32 +++++++++++++--------- 2 files changed, 68 insertions(+), 24 deletions(-) -- 2.20.1