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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 6BBCCC433DF for ; Wed, 17 Jun 2020 20:27:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F91E21548 for ; Wed, 17 Jun 2020 20:27:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726868AbgFQU1r (ORCPT ); Wed, 17 Jun 2020 16:27:47 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:29098 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726758AbgFQU1q (ORCPT ); Wed, 17 Jun 2020 16:27:46 -0400 X-IronPort-AV: E=Sophos;i="5.73,523,1583190000"; d="scan'208";a="455254845" Received: from abo-173-121-68.mrs.modulonet.fr (HELO hadrien) ([85.68.121.173]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jun 2020 22:27:43 +0200 Date: Wed, 17 Jun 2020 22:27:43 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Denis Efremov cc: linux-kernel@vger.kernel.org, cocci@systeme.lip6.fr Subject: Re: [Cocci] [PATCH] coccinelle: api: add device_attr_show script In-Reply-To: <20200615130242.11825-1-efremov@linux.com> Message-ID: References: <20200615130242.11825-1-efremov@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 Mon, 15 Jun 2020, Denis Efremov wrote: > According to the documentation[1] show() methods of device attributes > should return the number of bytes printed into the buffer. This is > the return value of scnprintf(). show() must not use snprintf() > when formatting the value to be returned to user space. snprintf() > returns the length the resulting string would be, assuming it all > fit into the destination array[2]. scnprintf() return the length of > the string actually created in buf. If one can guarantee that an > overflow will never happen sprintf() can be used otherwise scnprintf(). The semantic patch looks fine. Do you have any accepted patches from this? julia > > [1] Documentation/filesystems/sysfs.txt > [2] "snprintf() confusion" https://lwn.net/Articles/69419/ > > Signed-off-by: Denis Efremov > --- > scripts/coccinelle/api/device_attr_show.cocci | 55 +++++++++++++++++++ > 1 file changed, 55 insertions(+) > create mode 100644 scripts/coccinelle/api/device_attr_show.cocci > > diff --git a/scripts/coccinelle/api/device_attr_show.cocci b/scripts/coccinelle/api/device_attr_show.cocci > new file mode 100644 > index 000000000000..d8ec4bb8ac41 > --- /dev/null > +++ b/scripts/coccinelle/api/device_attr_show.cocci > @@ -0,0 +1,55 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/// > +/// From Documentation/filesystems/sysfs.txt: > +/// show() must not use snprintf() when formatting the value to be > +/// returned to user space. If you can guarantee that an overflow > +/// will never happen you can use sprintf() otherwise you must use > +/// scnprintf(). > +/// > +// Confidence: High > +// Copyright: (C) 2020 Denis Efremov ISPRAS > +// Options: --no-includes --include-headers > +// > + > +virtual report > +virtual org > +virtual context > +virtual patch > + > +@r depends on !patch@ > +identifier show, dev, attr, buf; > +position p; > +@@ > + > +ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) > +{ > + <... > +* return snprintf@p(...); > + ...> > +} > + > +@rp depends on patch@ > +identifier show, dev, attr, buf; > +@@ > + > +ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) > +{ > + <... > + return > +- snprintf > ++ scnprintf > + (...); > + ...> > +} > + > +@script: python depends on report@ > +p << r.p; > +@@ > + > +coccilib.report.print_report(p[0], "WARNING: use scnprintf or sprintf") > + > +@script: python depends on org@ > +p << r.p; > +@@ > + > +coccilib.org.print_todo(p[0], "WARNING: use scnprintf or sprintf") > -- > 2.26.2 > > _______________________________________________ > Cocci mailing list > Cocci@systeme.lip6.fr > https://systeme.lip6.fr/mailman/listinfo/cocci >