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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 46581C432BE for ; Thu, 2 Sep 2021 14:05:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CA11610E6 for ; Thu, 2 Sep 2021 14:05:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345460AbhIBOGL convert rfc822-to-8bit (ORCPT ); Thu, 2 Sep 2021 10:06:11 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]:27180 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345370AbhIBOEU (ORCPT ); Thu, 2 Sep 2021 10:04:20 -0400 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-90-tzR3TaFjMtSaC8iSrW3zwg-1; Thu, 02 Sep 2021 15:03:18 +0100 X-MC-Unique: tzR3TaFjMtSaC8iSrW3zwg-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Thu, 2 Sep 2021 15:03:17 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.023; Thu, 2 Sep 2021 15:03:17 +0100 From: David Laight To: 'Joe Perches' , Kari Argillander , Konstantin Komarov , "ntfs3@lists.linux.dev" CC: "linux-kernel@vger.kernel.org" Subject: RE: [PATCH 1/5] fs/ntfs3: Use kmalloc_array over kmalloc with multiply Thread-Topic: [PATCH 1/5] fs/ntfs3: Use kmalloc_array over kmalloc with multiply Thread-Index: AQHXntrPdHiUovXUwEmoBRmrkk5W9KuQyAlw Date: Thu, 2 Sep 2021 14:03:17 +0000 Message-ID: <6c078835254b43ec82bf45db3b241510@AcuMS.aculab.com> References: <20210831181505.1074767-1-kari.argillander@gmail.com> <20210831181505.1074767-2-kari.argillander@gmail.com> <5197939870d1867dd2131a8fdff8842b777c6016.camel@perches.com> In-Reply-To: <5197939870d1867dd2131a8fdff8842b777c6016.camel@perches.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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com 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: Joe Perches > Sent: 01 September 2021 03:41 > > On Tue, 2021-08-31 at 21:15 +0300, Kari Argillander wrote: > > If we do not use kmalloc_array we get checkpatch warning. It is also > > little safer if something goes wrong with coding. > [] > > diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c > [] > > @@ -707,7 +707,7 @@ static struct NTFS_DE *hdr_find_e(const struct ntfs_index *indx, > >   u16 *ptr; > >   int new_slots = ALIGN(2 * nslots, 8); > > > > > > - ptr = kmalloc(sizeof(u16) * new_slots, GFP_NOFS); > > + ptr = kmalloc_array(new_slots, sizeof(u16), GFP_NOFS); > >   if (ptr) > >   memcpy(ptr, offs, sizeof(u16) * max_idx); > > This multiplication could also overflow. Not if kmalloc_array() has suceeded. OTOH the ALIGN(2 * nslots, 8) can also go wrong. (But probably not if the previous kmalloc() for 1/2 the size worked.) But there really ought to be some kind of bound check earlier. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)