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=-4.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 8E671C433E6 for ; Thu, 27 Aug 2020 22:17:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6572C2087E for ; Thu, 27 Aug 2020 22:17:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Sn1Xn765" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726953AbgH0WQ7 (ORCPT ); Thu, 27 Aug 2020 18:16:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726234AbgH0WQ7 (ORCPT ); Thu, 27 Aug 2020 18:16:59 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 403CEC061264 for ; Thu, 27 Aug 2020 15:16:59 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id mt12so3367113pjb.4 for ; Thu, 27 Aug 2020 15:16:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=lLmbzoSbX37WRFYQW3L/1ffMVUDf88bIb2L15ySX4bI=; b=Sn1Xn765zecNGssYNGAzm6wFGVk/ZUhv3yF24YKSHrrm6U0gqIZZZDxVzDAyNtP0T4 cXAMTSit0hEdTaUdP8eWW8XSdX0PhQMN7+d7nso/G2BMTeqMHmL3Cdk9S54CZ6SMe7Zl DkBln/HezvkLX2GPBY0Q+sV4MPupwJjvZ0xzE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=lLmbzoSbX37WRFYQW3L/1ffMVUDf88bIb2L15ySX4bI=; b=tNGh00YPMYwWNW/IL3m3Kpbp/njnogfXBO78Dl9Dte7qjfr67c+rAqfzyfgPLxO+Vy 1ujIbYfSIjKKrd279bgw1plnn2x9WkEY341bvUgPbx01/Afjh7b+rZqeuza2i9v1GrTT KNp5CbsoM4JnlWt1Tlu41+gXsT/FJPMSsgfcS3HhIDTWgy+90/F5siRVga302lOQUJaN EBlFJdgt+n17ch38Ogk1JEl1ZY5DQh0t76lTzWjzFwh+VBzfytGqll4FNFie92WzIn90 Goq3Yhc3PPc089K4K+sr5IGmBjTBR7CGwZ++8Xo4Vl/RZemVsoFJlpvLwuuM2g+u0vqN ptAw== X-Gm-Message-State: AOAM5316MH50u++fyEBZqeOcBu3zTr/0VQ/8W3u5cMlwbAhxgoAW7D6s KOYPmoCqOENmkkPUgqpu/DPgTQ== X-Google-Smtp-Source: ABdhPJxc4Utn2CJ+IfyCfdMPjgDjTvD7I3FRBoJwWEMSO3xb8hDq51v6hjQN8kpG25RPcBppMWR8wg== X-Received: by 2002:a17:90a:19c2:: with SMTP id 2mr845122pjj.6.1598566618642; Thu, 27 Aug 2020 15:16:58 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id lw2sm3005169pjb.34.2020.08.27.15.16.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Aug 2020 15:16:57 -0700 (PDT) Date: Thu, 27 Aug 2020 15:16:56 -0700 From: Kees Cook To: Joe Perches Cc: David Laight , Julia Lawall , Alex Dewar , Rasmus Villemoes , cocci , Greg Kroah-Hartman , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Gustavo A. R. Silva" , "accessrunner-general@lists.sourceforge.net" Subject: Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs Message-ID: <202008271516.ED209B68@keescook> References: <48f2dc90-7852-eaf1-55d7-2c85cf954688@rasmusvillemoes.dk> <20200827071537.GA168593@kroah.com> <20200827131819.7rcl2f5js3hkoqj2@lenovo-laptop> <20200827144846.yauuttjaqtxaldxg@lenovo-laptop> <5d1dfb9b031130d4d20763ec621233a19d6a88a2.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Thu, Aug 27, 2020 at 03:11:57PM -0700, Joe Perches wrote: > On Thu, 2020-08-27 at 22:03 +0000, David Laight wrote: > > From: Joe Perches > > > Sent: 27 August 2020 21:30 > > ... > > > Perhaps what's necessary is to find any > > > appropriate .show function and change > > > any use of strcpy/sprintf within those > > > function to some other name. > > > > > > For instance: > > > > > > drivers/isdn/mISDN/core.c-static ssize_t name_show(struct device *dev, > > > drivers/isdn/mISDN/core.c- struct device_attribute *attr, char *buf) > > > drivers/isdn/mISDN/core.c-{ > > > drivers/isdn/mISDN/core.c: strcpy(buf, dev_name(dev)); > > > drivers/isdn/mISDN/core.c- return strlen(buf); > > > drivers/isdn/mISDN/core.c-} > > > drivers/isdn/mISDN/core.c-static DEVICE_ATTR_RO(name); > > > > That form ends up calculating the string length twice. > > Better would be: > > len = strlen(msg); > > memcpy(buf, msg, len); > > return len; > > or given clang's requirement for stpcpy > > return stpcpy(buf, dev_name(dev)) - buf; > > (I do not advocate for this ;) Heh. And humans aren't allowed to use stpcpy() in the kernel. :) -- Kees Cook