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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC8EFC433FE for ; Tue, 1 Nov 2022 13:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbiKANfh convert rfc822-to-8bit (ORCPT ); Tue, 1 Nov 2022 09:35:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229898AbiKANfa (ORCPT ); Tue, 1 Nov 2022 09:35:30 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E323219B for ; Tue, 1 Nov 2022 06:35:28 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-38-tp3SBBnYM7uN9vRSuxgg_A-1; Tue, 01 Nov 2022 13:35:25 +0000 X-MC-Unique: tp3SBBnYM7uN9vRSuxgg_A-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Tue, 1 Nov 2022 13:35:24 +0000 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.042; Tue, 1 Nov 2022 13:35:24 +0000 From: David Laight To: 'Mark Rutland' CC: 'Szabolcs Nagy' , 'Theodore Ts'o' , "'linux-api@vger.kernel.org'" , "'linux-kernel@vger.kernel.org'" , "'linux-arm-kernel@lists.infradead.org'" Subject: RE: linux interprets an fcntl int arg as long Thread-Topic: linux interprets an fcntl int arg as long Thread-Index: AQHY7dH4b5GlkmHz9EyVI+/nub6Ts64p0qEQgAAgcACAAAds0IAAERqAgAADzNCAAAIMcA== Date: Tue, 1 Nov 2022 13:35:23 +0000 Message-ID: References: <0030a20a94cd49628c5461d044bb28ed@AcuMS.aculab.com> <267402c9e66a4cac91a2e1df749dea6a@AcuMS.aculab.com> In-Reply-To: <267402c9e66a4cac91a2e1df749dea6a@AcuMS.aculab.com> Accept-Language: en-GB, 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-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Laight > Sent: 01 November 2022 13:30 > > From: Mark Rutland > > Sent: 01 November 2022 13:13 > > > > On Tue, Nov 01, 2022 at 12:19:51PM +0000, David Laight wrote: > > > From: 'Szabolcs Nagy' > > > > Sent: 01 November 2022 11:45 > > > > > > > > The 11/01/2022 10:02, David Laight wrote: > > > > > From: Szabolcs Nagy > > > > > > kernel code: > > > > ------------ > > > > SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) > > > > { > > > > > > That is just a wrapper and calls do_fcntl(). > > > which needs changing to be add: > > > arg &= ~0U; > > > before the switch(cmd) { > > > > Just to check, do you mean the switch in do_fcntl(), or the switch within memfd_fcntl() ? > > > > The former handles other APIs which do expect arg to be a long (e.g. > > F_SET_RW_HINT and F_GET_RW_HINT expect it to hold a full 64-bit pointer), so > > that'd break things. > > The assignment to argv is earlier. Clearly I meant argp :-) Alternatively all the helper functions should be changed to have an 'unsigned int' argument instead of 'unsigned long'. That might show up any that try to read user buffers. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)