From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=kGB5=CE=vger.kernel.org=linux-kernel-owner@kernel.org>
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=-3.8 required=3.0 tests=BAYES_00,
	HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS
	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 E29D0C433DF
	for <linux-kernel@archiver.kernel.org>; Wed, 26 Aug 2020 16:57:40 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by mail.kernel.org (Postfix) with ESMTP id C196A2078B
	for <linux-kernel@archiver.kernel.org>; Wed, 26 Aug 2020 16:57:40 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1727049AbgHZQ5j (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Wed, 26 Aug 2020 12:57:39 -0400
Received: from smtprelay0106.hostedemail.com ([216.40.44.106]:40492 "EHLO
        smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL)
        by vger.kernel.org with ESMTP id S1727020AbgHZQ5d (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 26 Aug 2020 12:57:33 -0400
Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60])
        by smtprelay08.hostedemail.com (Postfix) with ESMTP id 32FB3182CED2A;
        Wed, 26 Aug 2020 16:57:32 +0000 (UTC)
X-Session-Marker: 6A6F6540706572636865732E636F6D
X-HE-Tag: doll88_0d0bccf27066
X-Filterd-Recvd-Size: 1836
Received: from XPS-9350.home (unknown [47.151.133.149])
        (Authenticated sender: joe@perches.com)
        by omf14.hostedemail.com (Postfix) with ESMTPA;
        Wed, 26 Aug 2020 16:57:29 +0000 (UTC)
Message-ID: <d56bf7b93f7a28c4a90e4e16fd412e6934704346.camel@perches.com>
Subject: Re: [PATCH v3] lib/string.c: implement stpcpy
From:   Joe Perches <joe@perches.com>
To:     Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>
Cc:     clang-built-linux <clang-built-linux@googlegroups.com>,
        stable <stable@vger.kernel.org>, Andy Lavr <andy.lavr@gmail.com>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Sami Tolvanen <samitolvanen@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Alexandru Ardelean <alexandru.ardelean@analog.com>,
        Yury Norov <yury.norov@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date:   Wed, 26 Aug 2020 09:57:28 -0700
In-Reply-To: <CAK7LNAQXo5-5W6hvNMEVPBPf3tRWaf-pQdSR-0OHyi4RCGhjsQ@mail.gmail.com>
References: <20200825135838.2938771-1-ndesaulniers@google.com>
         <CAK7LNAQXo5-5W6hvNMEVPBPf3tRWaf-pQdSR-0OHyi4RCGhjsQ@mail.gmail.com>
Content-Type: text/plain; charset="ISO-8859-1"
User-Agent: Evolution 3.36.4-0ubuntu1 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 2020-08-27 at 01:49 +0900, Masahiro Yamada wrote:
> I do not have time to keep track of the discussion fully,
> but could you give me a little more context why
> the usage of stpcpy() is not recommended ?
> 
> The implementation of strcpy() is almost the same.
> It is unclear to me what makes stpcpy() unsafe..

It's the same thing that makes strcpy unsafe:

Unchecked buffer lengths with no guarantee src is terminated.