From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:39768 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729758AbeJKXJG (ORCPT ); Thu, 11 Oct 2018 19:09:06 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Ben Hutchings , Greg Hackmann Subject: [PATCH 3.18 111/120] ext4: fix false negatives *and* false positives in ext4_check_descriptors() Date: Thu, 11 Oct 2018 17:34:52 +0200 Message-Id: <20181011152554.384536691@linuxfoundation.org> In-Reply-To: <20181011152549.500488630@linuxfoundation.org> References: <20181011152549.500488630@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 44de022c4382541cebdd6de4465d1f4f465ff1dd upstream. Ext4_check_descriptors() was getting called before s_gdb_count was initialized. So for file systems w/o the meta_bg feature, allocation bitmaps could overlap the block group descriptors and ext4 wouldn't notice. For file systems with the meta_bg feature enabled, there was a fencepost error which would cause the ext4_check_descriptors() to incorrectly believe that the block allocation bitmap overlaps with the block group descriptor blocks, and it would reject the mount. Fix both of these problems. Signed-off-by: Theodore Ts'o [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Greg Hackmann Signed-off-by: Greg Kroah-Hartman --- fs/ext4/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2064,7 +2064,7 @@ static int ext4_check_descriptors(struct struct ext4_sb_info *sbi = EXT4_SB(sb); ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block); ext4_fsblk_t last_block; - ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0) + 1; + ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0); ext4_fsblk_t block_bitmap; ext4_fsblk_t inode_bitmap; ext4_fsblk_t inode_table; @@ -4018,12 +4018,12 @@ static int ext4_fill_super(struct super_ goto failed_mount2; } } + sbi->s_gdb_count = db_count; if (!ext4_check_descriptors(sb, logical_sb_block, &first_not_zeroed)) { ext4_msg(sb, KERN_ERR, "group descriptors corrupted!"); goto failed_mount2; } - sbi->s_gdb_count = db_count; get_random_bytes(&sbi->s_next_generation, sizeof(u32)); spin_lock_init(&sbi->s_next_gen_lock);