From patchwork Fri Jun 24 08:58:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zheng Lv X-Patchwork-Id: 9196981 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 211BC6077D for ; Fri, 24 Jun 2016 09:00:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0D4F528481 for ; Fri, 24 Jun 2016 09:00:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F3B2F28498; Fri, 24 Jun 2016 09:00:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8A9FE28481 for ; Fri, 24 Jun 2016 09:00:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751476AbcFXJAZ (ORCPT ); Fri, 24 Jun 2016 05:00:25 -0400 Received: from mail-qk0-f196.google.com ([209.85.220.196]:34070 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751465AbcFXJAW (ORCPT ); Fri, 24 Jun 2016 05:00:22 -0400 Received: by mail-qk0-f196.google.com with SMTP id j2so19999370qkf.1 for ; Fri, 24 Jun 2016 02:00:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=YWvBM4wZXHflc3Ck3912KYc6FJpW5FHkSdS8Lazz7Ec=; b=GFBQFsF+w8Y+YkON2/KyR9K3lQl1niklRFtn67PAOQOPsVRoCcmzexA2OAcgY6g3ck cEwyH9FVF3r30M/l4SSA6Pr/z1U0TTDlK03gpcKUg9JfVSTosGmKb8r/CpsX73E1Ke7a bDhtmwj99jyKRt/XI/XSRvZbrtcT71DO7yTiZ/c1ITcaLtapREJ+7lQKLKkhlXlY0pFh UJuixPEv1RDVeTsd3m8WPKENR/OH0Q7vYO5h1gvRKiV2fmBf9HaVdB3zvXS9KNJnnlid dCsRbdU5Rywyct24USyf9d/kujC0P5c5SsXa5WTdJR93KN1Z6go6M6d35edLvgGBuUEB D0Cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=YWvBM4wZXHflc3Ck3912KYc6FJpW5FHkSdS8Lazz7Ec=; b=JhGAGy0fpaOQK4STvvoBAPHY4AEOfNXdU4ZQNFTdUULOUiqMCLzgzx9hbFwxO7rRB6 LMWSu0aIzCu1VIjIhqyU3lnEw6cdAHZ6VPiEJJmtaeWhCGZZn3wxCj83Df9NtcI3XOtt sNM2t4BXxbHOBLztDAVqK5fL2EWD2UE9+BwyCpMtF9nJfY9vqJ47tkr9JPuRGmLwGRh9 pHeQuLcmScA2Pr1PSMECtTxB1AjMKIy9QVaI3w5ZjYeqpvf7ZjUI8FdoNS8GYTUUEk9b a5Eb6h4gto7bNYZ/54CphOcQ4eca9/U+8LzQAJ2qOztckmzKLAeIvacsJhTy9vQGL6fm 9+Dg== X-Gm-Message-State: ALyK8tJ7zwyYBOaW2AqxmV6TLaBaZtXW8XZKpuTk3vWV9jGj7sHOB2ivXik9KnONBShztg== X-Received: by 10.55.25.155 with SMTP id 27mr3346486qkz.61.1466758816035; Fri, 24 Jun 2016 02:00:16 -0700 (PDT) Received: from localhost.localdomain ([162.243.234.82]) by smtp.gmail.com with ESMTPSA id 23sm1785664qty.40.2016.06.24.02.00.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 24 Jun 2016 02:00:15 -0700 (PDT) From: Zheng Lv To: hirofumi@mail.parknet.co.jp Cc: linux-fsdevel@vger.kernel.org Subject: [PATCH] fat: check whether fs size exceeds device size Date: Fri, 24 Jun 2016 04:58:10 -0400 Message-Id: <1466758690-12354-1-git-send-email-lv.zheng.2015@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The original code did not check for size of device. A truncated device would mount, I/O failures would occur when "attempt to access beyond end of device", leading to data lost. Fix this by comparing total-sectors field in BPB with size of device. This commit also prints a KERN_INFO message if there are extra sectors at end of device (ie. total sectors < device sectors). Signed-off-by: Zheng Lv --- fs/fat/inode.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 3bcf579..211f7bb 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1583,6 +1583,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, struct msdos_sb_info *sbi; u16 logical_sector_size; u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors; + u64 device_sectors; int debug; long error; char buf[50]; @@ -1738,6 +1739,17 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, if (total_sectors == 0) total_sectors = bpb.fat_total_sect; + device_sectors = sb->s_bdev->bd_inode->i_size / logical_sector_size; + if (device_sectors && total_sectors > device_sectors) { + fat_msg(sb, KERN_ERR, "total sectors %u " + "exceeds size of device (%llu sectors)", + total_sectors, device_sectors); + goto out_invalid; + } else if (device_sectors && total_sectors < device_sectors) { + fat_msg(sb, KERN_INFO, "%llu unused sectors at end of device", + device_sectors - total_sectors); + } + total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus; if (sbi->fat_bits != 32)