From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by kanga.kvack.org (Postfix) with ESMTP id A6B3F6B6E65 for ; Tue, 4 Sep 2018 12:24:24 -0400 (EDT) Received: by mail-wr1-f72.google.com with SMTP id d10-v6so4131755wrw.6 for ; Tue, 04 Sep 2018 09:24:24 -0700 (PDT) Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-db5eur01on0108.outbound.protection.outlook.com. [104.47.2.108]) by mx.google.com with ESMTPS id n17-v6si19414484wra.263.2018.09.04.09.24.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 04 Sep 2018 09:24:23 -0700 (PDT) Subject: Re: [PATCH v2] arm64: kasan: add interceptors for strcmp/strncmp functions From: Andrey Ryabinin References: <1535014606-176525-1-git-send-email-kyeongdon.kim@lge.com> <6954711c-6441-04df-62a9-a83c867e06ad@virtuozzo.com> Message-ID: <12d4e435-e229-b4af-4286-a53fa77cb09d@virtuozzo.com> Date: Tue, 4 Sep 2018 19:24:33 +0300 MIME-Version: 1.0 In-Reply-To: <6954711c-6441-04df-62a9-a83c867e06ad@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Kyeongdon Kim 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 On 09/04/2018 01:10 PM, Andrey Ryabinin wrote: > > > On 09/04/2018 09:59 AM, Kyeongdon Kim wrote: > >>>> +#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) >> A EXPORT_SYMBOL(strlcat); >> A #endif >> >> -#ifndef __HAVE_ARCH_STRCMP >> +#if (defined(CONFIG_ARM64) && defined(CONFIG_KASAN)) || !defined(__HAVE_ARCH_STRCMP) > > No. What part of "like you did in your first patch" is unclear to you? Just to be absolutely clear, I meant #ifdef out __HAVE_ARCH_* defines like it has been done in this patch http://lkml.kernel.org/r/<1534233322-106271-1-git-send-email-kyeongdon.kim@lge.com>