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_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 E377EC433F5 for ; Mon, 3 Sep 2018 07:17:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EE9D20843 for ; Mon, 3 Sep 2018 07:17:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EE9D20843 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mail.parknet.co.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbeICLgT (ORCPT ); Mon, 3 Sep 2018 07:36:19 -0400 Received: from mail.parknet.co.jp ([210.171.160.6]:54834 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725794AbeICLgT (ORCPT ); Mon, 3 Sep 2018 07:36:19 -0400 Received: from ibmpc.myhome.or.jp (server.parknet.ne.jp [210.171.168.39]) by mail.parknet.co.jp (Postfix) with ESMTPSA id D4C5515AF4B; Mon, 3 Sep 2018 16:17:28 +0900 (JST) Received: from devron.myhome.or.jp (foobar@devron.myhome.or.jp [192.168.0.3]) by ibmpc.myhome.or.jp (8.15.2/8.15.2/Debian-11) with ESMTPS id w837HR4q018546 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 3 Sep 2018 16:17:28 +0900 Received: from devron.myhome.or.jp (foobar@localhost [127.0.0.1]) by devron.myhome.or.jp (8.15.2/8.15.2/Debian-11) with ESMTPS id w837HRw5001540 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 3 Sep 2018 16:17:27 +0900 Received: (from hirofumi@localhost) by devron.myhome.or.jp (8.15.2/8.15.2/Submit) id w837HRrM001539; Mon, 3 Sep 2018 16:17:27 +0900 From: OGAWA Hirofumi To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] fat: Relax checks for sector size and media type References: <20180902131932.11558-1-pali.rohar@gmail.com> Date: Mon, 03 Sep 2018 16:17:26 +0900 In-Reply-To: <20180902131932.11558-1-pali.rohar@gmail.com> ("Pali =?iso-8859-1?Q?Roh=E1r=22's?= message of "Sun, 2 Sep 2018 15:19:32 +0200") Message-ID: <87bm9ft5h5.fsf@mail.parknet.co.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pali Rohár writes: > Windows fastfat.sys driver accepts also media types 0x00 and 0x01 and > sector sizes 128 and 256 bytes. Linux mkfs.fat can format disk also to > larger FAT sector sizes then 4096 bytes, therefore relax also upper limit > restriction. > - if (!is_power_of_2(bpb->fat_sector_size) > - || (bpb->fat_sector_size < 512) > - || (bpb->fat_sector_size > 4096)) { > + if (!is_power_of_2(bpb->fat_sector_size)) { Just relaxing validation doesn't work. The block layer doesn't support smaller than 512, and lager than PAGE_SIZE. (And in specification, fat doesn't support lager than 4096.) > static inline int fat_valid_media(u8 media) > { > - return 0xf8 <= media || media == 0xf0; > + return 0xf8 <= media || media == 0xf0 || media == 0x00 || media == 0x01; > } > #endif /* !_LINUX_MSDOS_FS_H */ This is ok though, this would be for ancient floppy media. Thanks. -- OGAWA Hirofumi