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=-0.8 required=3.0 tests=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 4639EC3F2CD for ; Mon, 23 Mar 2020 15:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1606A206F8 for ; Mon, 23 Mar 2020 15:11:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727240AbgCWPLq convert rfc822-to-8bit (ORCPT ); Mon, 23 Mar 2020 11:11:46 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:32604 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727096AbgCWPLp (ORCPT ); Mon, 23 Mar 2020 11:11:45 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-117-FP7y-fD7Or6NzgHxkL5fNw-1; Mon, 23 Mar 2020 15:11:41 +0000 X-MC-Unique: FP7y-fD7Or6NzgHxkL5fNw-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 23 Mar 2020 15:11:40 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 23 Mar 2020 15:11:40 +0000 From: David Laight To: 'Christophe JAILLET' , "peterz@infradead.org" , "mingo@redhat.com" , "acme@kernel.org" , "mark.rutland@arm.com" , "alexander.shishkin@linux.intel.com" , "jolsa@redhat.com" , "namhyung@kernel.org" , "kan.liang@linux.intel.com" , "zhe.he@windriver.com" , "dzickus@redhat.com" , "jstancek@redhat.com" CC: "linux-kernel@vger.kernel.org" , "kernel-janitors@vger.kernel.org" Subject: RE: [PATCH] perf cpumap: Use scnprintf instead of snprintf Thread-Topic: [PATCH] perf cpumap: Use scnprintf instead of snprintf Thread-Index: AQHWAG7rOhePTwQGyk2fyROkdMOaUqhWSN8A Date: Mon, 23 Mar 2020 15:11:40 +0000 Message-ID: References: <20200322172523.2677-1-christophe.jaillet@wanadoo.fr> In-Reply-To: <20200322172523.2677-1-christophe.jaillet@wanadoo.fr> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christophe JAILLET > Sent: 22 March 2020 17:25 > 'scnprintf' returns the number of characters written in the output buffer > excluding the trailing '\0', instead of the number of characters which > would be generated for the given input. > > Both function return a number of characters, excluding the trailing '\0'. > So comparaison to check if it overflows, should be done against max_size-1. > Comparaison against max_size can never match. NACK. Since snprintf() returns the number of characters it would have written to an infinite buffer the comparison can 'match'. However it should test for (ret >= PATH_MAX). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)