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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 49561C433E2 for ; Thu, 27 Aug 2020 22:46:07 +0000 (UTC) Received: from isis.lip6.fr (isis.lip6.fr [132.227.60.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BF40F20848 for ; Thu, 27 Aug 2020 22:46:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF40F20848 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=perches.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=cocci-bounces@systeme.lip6.fr Received: from systeme.lip6.fr (systeme.lip6.fr [132.227.104.7]) by isis.lip6.fr (8.15.2/8.15.2) with ESMTP id 07RMjRXF025424; Fri, 28 Aug 2020 00:45:27 +0200 (CEST) Received: from systeme.lip6.fr (systeme.lip6.fr [127.0.0.1]) by systeme.lip6.fr (Postfix) with ESMTP id ACCB34316; Fri, 28 Aug 2020 00:45:27 +0200 (CEST) Received: from isis.lip6.fr (isis.lip6.fr [132.227.60.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by systeme.lip6.fr (Postfix) with ESMTPS id D2C8E3C97 for ; Fri, 28 Aug 2020 00:45:25 +0200 (CEST) Received: from smtprelay.hostedemail.com (smtprelay0224.hostedemail.com [216.40.44.224]) by isis.lip6.fr (8.15.2/8.15.2) with ESMTPS id 07RMjO2I000809 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 28 Aug 2020 00:45:25 +0200 (CEST) Received: from smtprelay.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by smtpgrave05.hostedemail.com (Postfix) with ESMTP id 1B3D9180339AE for ; Thu, 27 Aug 2020 22:45:24 +0000 (UTC) Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay05.hostedemail.com (Postfix) with ESMTP id DB2FD180339CD; Thu, 27 Aug 2020 22:45:20 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: pies81_1b16d5127070 X-Filterd-Recvd-Size: 3013 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf15.hostedemail.com (Postfix) with ESMTPA; Thu, 27 Aug 2020 22:45:19 +0000 (UTC) Message-ID: <5ebe5c2737b59d04f1b8a46008cd3159c638f9d0.camel@perches.com> From: Joe Perches To: Kees Cook , Denis Efremov Date: Thu, 27 Aug 2020 15:45:17 -0700 In-Reply-To: <202008271517.ECC1F1F8F@keescook> 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> <202008271517.ECC1F1F8F@keescook> User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 X-Greylist: Sender IP whitelisted, Sender e-mail whitelisted, not delayed by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Fri, 28 Aug 2020 00:45:27 +0200 (CEST) X-Greylist: Delayed for 00:33:19 by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Fri, 28 Aug 2020 00:45:25 +0200 (CEST) X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, Rasmus Villemoes , "Gustavo A. R. Silva" , linux-kernel@vger.kernel.org, Alex Dewar , cocci Subject: Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs X-BeenThere: cocci@systeme.lip6.fr X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: cocci-bounces@systeme.lip6.fr Errors-To: cocci-bounces@systeme.lip6.fr On Thu, 2020-08-27 at 15:20 -0700, Kees Cook wrote: > On Fri, Aug 28, 2020 at 12:01:34AM +0300, Denis Efremov wrote: > > 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. > > Agreed. This just makes me cringe. If the API design declares that when > a show() callback starts, buf has been allocated with PAGE_SIZE bytes, > then that's how the logic should proceed, and it should be using > scnprintf... > > show(...) { > size_t remaining = PAGE_SIZE; > > ... > remaining -= scnprintf(buf, remaining, "fmt", var args ...); > remaining -= scnprintf(buf, remaining, "fmt", var args ...); > remaining -= scnprintf(buf, remaining, "fmt", var args ...); > > return PAGE_SIZE - remaining; > } It seems likely that coccinelle could do those transform with any of sprintf/snprintf/scnprint too. Though my bikeshed would use a single function and have that function know the maximum output size Something like: With single line use: return sysfs_emit(buf, buf, fmt, ...) - buf; and multi-line use: char *pos = buf; pos = sysfs_emit(buf, pos, fmt1, ...); pos = sysfs_emit(buf, pos, fmt2, ...); ... return pos - buf; _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci