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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 414DFC433E2 for ; Thu, 27 Aug 2020 21:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1DBD52075B for ; Thu, 27 Aug 2020 21:36:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbgH0Vge (ORCPT ); Thu, 27 Aug 2020 17:36:34 -0400 Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:50702 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726073AbgH0Vgd (ORCPT ); Thu, 27 Aug 2020 17:36:33 -0400 X-IronPort-AV: E=Sophos;i="5.76,359,1592863200"; d="scan'208";a="357458750" Received: from abo-173-121-68.mrs.modulonet.fr (HELO hadrien) ([85.68.121.173]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Aug 2020 23:36:29 +0200 Date: Thu, 27 Aug 2020 23:36:28 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Denis Efremov cc: Julia Lawall , Joe Perches , "Gustavo A. R. Silva" , Kees Cook , Greg Kroah-Hartman , linux-usb@vger.kernel.org, Rasmus Villemoes , linux-kernel@vger.kernel.org, cocci , accessrunner-general@lists.sourceforge.net, Alex Dewar Subject: Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs In-Reply-To: <5853c58e-7d26-2cf9-6cbf-698ecd93cbf9@linux.com> Message-ID: References: <20200824222322.22962-1-alex.dewar90@gmail.com> <48f2dc90-7852-eaf1-55d7-2c85cf954688@rasmusvillemoes.dk> <20200827071537.GA168593@kroah.com> <20200827131819.7rcl2f5js3hkoqj2@lenovo-laptop> <20200827144846.yauuttjaqtxaldxg@lenovo-laptop> <5d1dfb9b031130d4d20763ec621233a19d6a88a2.camel@perches.com> <5853c58e-7d26-2cf9-6cbf-698ecd93cbf9@linux.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 28 Aug 2020, Denis Efremov wrote: > Hi all, > > On 8/27/20 10:42 PM, Julia Lawall wrote: > > > > > > On Thu, 27 Aug 2020, Joe Perches wrote: > > > >> On Thu, 2020-08-27 at 15:48 +0100, Alex Dewar wrote: > >>> On Thu, Aug 27, 2020 at 03:41:06PM +0200, Rasmus Villemoes wrote: > >>>> On 27/08/2020 15.18, Alex Dewar wrote: > >>>>> On Thu, Aug 27, 2020 at 09:15:37AM +0200, Greg Kroah-Hartman wrote: > >>>>>> On Thu, Aug 27, 2020 at 08:42:06AM +0200, Rasmus Villemoes wrote: > >>>>>>> On 25/08/2020 00.23, Alex Dewar wrote: > >>>>>>>> kernel/cpu.c: don't use snprintf() for sysfs attrs > >>>>>>>> > >>>>>>>> As per the documentation (Documentation/filesystems/sysfs.rst), > >>>>>>>> snprintf() should not be used for formatting values returned by sysfs. > > Just FYI, I've send an addition to the device_attr_show.cocci script[1] to turn > simple cases of snprintf (e.g. "%i") to sprintf. Looks like many developers would > like it more than changing snprintf to scnprintf. As for me, I don't like the idea > of automated altering of the original logic from bounded snprint to unbouded one > with sprintf. > > [1] https://lkml.org/lkml/2020/8/13/786 > > Regarding current device_attr_show.cocci implementation, it detects the functions > by declaration: > ssize_t any_name(struct device *dev, struct device_attribute *attr, char *buf) > > and I limited the check to: > "return snprintf" > pattern because there are already too many warnings. > > Actually, it looks more correct to check for: > ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > * snprintf@p(...); > ...> > } > > This pattern should also highlight the snprintf calls there we save returned > value in a var, e.g.: > > ret += snprintf(...); > ... > ret += snprintf(...); > ... > ret += snprintf(...); > > return ret; > > > > > Something like > > > > identifier f; > > fresh identifier = "sysfs" ## f; > > > > may be useful. Let me know if further help is needed. > > Initially, I wrote the rule to search for DEVICE_ATTR(..., ..., func_name, ...) This is what I would have expected. > functions. However, it looks like matching function prototype is enough. At least, > I failed to find false positives. I rejected the initial DEVICE_ATTR() searching > because I thought that it's impossible to handle DEVICE_ATTR_RO()/DEVICE_ATTR_RW() > macroses with coccinelle as they "generate" function names internally with > "##". "fresh identifier" should really help here, but now I doubt it's required in > device_attr_show.cocci, function prototype is enough. It's true that it is probably unique enough. julia