From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id MdjdA/RYGVvPBAAAmS7hNA ; Thu, 07 Jun 2018 16:10:56 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id A4FEE6089E; Thu, 7 Jun 2018 16:10:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 1A71D60115; Thu, 7 Jun 2018 16:10:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 1A71D60115 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936098AbeFGQKy (ORCPT + 25 others); Thu, 7 Jun 2018 12:10:54 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39175 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932973AbeFGOJB (ORCPT ); Thu, 7 Jun 2018 10:09:01 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvb1-0005Zi-FR; Thu, 07 Jun 2018 15:08:59 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvax-0002hd-Mg; Thu, 07 Jun 2018 15:08:55 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Theodore Ts'o" , "Ilya Dryomov" , "Lukas Czerner" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 020/410] ext4: fix bitmap position validation In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Czerner commit 22be37acce25d66ecf6403fc8f44df9c5ded2372 upstream. Currently in ext4_valid_block_bitmap() we expect the bitmap to be positioned anywhere between 0 and s_blocksize clusters, but that's wrong because the bitmap can be placed anywhere in the block group. This causes false positives when validating bitmaps on perfectly valid file system layouts. Fix it by checking whether the bitmap is within the group boundary. The problem can be reproduced using the following mkfs -t ext3 -E stride=256 /dev/vdb1 mount /dev/vdb1 /mnt/test cd /mnt/test wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz tar xf linux-4.16.3.tar.xz This will result in the warnings in the logs EXT4-fs error (device vdb1): ext4_validate_block_bitmap:399: comm tar: bg 84: block 2774529: invalid block bitmap [ Changed slightly for clarity and to not drop a overflow test -- TYT ] Signed-off-by: Lukas Czerner Signed-off-by: Theodore Ts'o Reported-by: Ilya Dryomov Fixes: 7dac4a1726a9 ("ext4: add validity checks for bitmap block numbers") Signed-off-by: Ben Hutchings --- fs/ext4/balloc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -323,6 +323,7 @@ static ext4_fsblk_t ext4_valid_block_bit struct ext4_sb_info *sbi = EXT4_SB(sb); ext4_grpblk_t offset; ext4_grpblk_t next_zero_bit; + ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb); ext4_fsblk_t blk; ext4_fsblk_t group_first_block; @@ -340,7 +341,7 @@ static ext4_fsblk_t ext4_valid_block_bit /* check whether block bitmap block number is set */ blk = ext4_block_bitmap(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) /* bad block bitmap */ return blk; @@ -348,7 +349,7 @@ static ext4_fsblk_t ext4_valid_block_bit /* check whether the inode bitmap block number is set */ blk = ext4_inode_bitmap(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) /* bad block bitmap */ return blk; @@ -356,8 +357,8 @@ static ext4_fsblk_t ext4_valid_block_bit /* check whether the inode table block number is set */ blk = ext4_inode_table(sb, desc); offset = blk - group_first_block; - if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize || - EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize) + if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || + EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit) return blk; next_zero_bit = ext4_find_next_zero_bit(bh->b_data, EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),