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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 3ACC1C43334 for ; Tue, 4 Sep 2018 06:59:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0007C20652 for ; Tue, 4 Sep 2018 06:59:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0007C20652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lge.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726355AbeIDLXF (ORCPT ); Tue, 4 Sep 2018 07:23:05 -0400 Received: from lgeamrelo12.lge.com ([156.147.23.52]:60797 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726041AbeIDLXF (ORCPT ); Tue, 4 Sep 2018 07:23:05 -0400 Received: from unknown (HELO lgemrelse6q.lge.com) (156.147.1.121) by 156.147.23.52 with ESMTP; 4 Sep 2018 15:59:19 +0900 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: kyeongdon.kim@lge.com Received: from unknown (HELO ?10.159.80.93?) (10.159.80.93) by 156.147.1.121 with ESMTP; 4 Sep 2018 15:59:18 +0900 X-Original-SENDERIP: 10.159.80.93 X-Original-MAILFROM: kyeongdon.kim@lge.com Subject: Re: Re: [PATCH v2] arm64: kasan: add interceptors for strcmp/strncmp functions To: Andrey Ryabinin Cc: catalin.marinas@arm.com, will.deacon@arm.com, glider@google.com, dvyukov@google.com, Jason@zx2c4.com, robh@kernel.org, ard.biesheuvel@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org References: <1535014606-176525-1-git-send-email-kyeongdon.kim@lge.com> From: Kyeongdon Kim Message-ID: Date: Tue, 4 Sep 2018 15:59:17 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Andrey, Thanks for your review. On 2018-09-03 오후 6:40, Andrey Ryabinin wrote: > > > On 08/23/2018 11:56 AM, Kyeongdon Kim wrote: > > > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c > > index c3bd520..61ad7f1 100644 > > --- a/mm/kasan/kasan.c > > +++ b/mm/kasan/kasan.c > > @@ -304,6 +304,29 @@ void *memcpy(void *dest, const void *src, > size_t len) > > > > return __memcpy(dest, src, len); > > } > > +#ifdef CONFIG_ARM64 > > +/* > > + * Arch arm64 use assembly variant for strcmp/strncmp, > > + * xtensa use inline asm operations and x86_64 use c one, > > + * so now this interceptors only for arm64 kasan. > > + */ > > +#undef strcmp > > +int strcmp(const char *cs, const char *ct) > > +{ > > + check_memory_region((unsigned long)cs, 1, false, _RET_IP_); > > + check_memory_region((unsigned long)ct, 1, false, _RET_IP_); > > + > > Well this is definitely wrong. strcmp() often accesses far more than > one byte. > > > + return __strcmp(cs, ct); > > +} > > +#undef strncmp > > +int strncmp(const char *cs, const char *ct, size_t len) > > +{ > > + check_memory_region((unsigned long)cs, len, false, _RET_IP_); > > + check_memory_region((unsigned long)ct, len, false, _RET_IP_); > > This will cause false positives. Both 'cs', and 'ct' could be less > than len bytes. > > There is no need in these interceptors, just use the C implementations > from lib/string.c > like you did in your first patch. > The only thing that was wrong in the first patch is that assembly > implementations > were compiled out instead of being declared week. > Well, at first I thought so.. I would remove diff code in /mm/kasan/kasan.c then use C implementations in lib/string.c w/ assem implementations as weak : diff --git a/lib/string.c b/lib/string.c index 2c0900a..a18b18f 100644 --- a/lib/string.c +++ b/lib/string.c @@ -312,7 +312,7 @@ size_t strlcat(char *dest, const char *src, size_t count)  EXPORT_SYMBOL(strlcat);  #endif -#ifndef __HAVE_ARCH_STRCMP +#if (defined(CONFIG_ARM64) && defined(CONFIG_KASAN)) || !defined(__HAVE_ARCH_STRCMP)  /**   * strcmp - Compare two strings   * @cs: One string @@ -336,7 +336,7 @@ int strcmp(const char *cs, const char *ct)  EXPORT_SYMBOL(strcmp);  #endif -#ifndef __HAVE_ARCH_STRNCMP +#if (defined(CONFIG_ARM64) && defined(CONFIG_KASAN)) || !defined(__HAVE_ARCH_STRNCMP)  /**   * strncmp - Compare two length-limited strings Can I get your opinion wrt this ? Thanks,