From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59820 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756785AbeDVOTh (ORCPT ); Sun, 22 Apr 2018 10:19:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Harsh Shandilya Subject: [PATCH 4.4 74/97] ext4: dont allow r/w mounts if metadata blocks overlap the superblock Date: Sun, 22 Apr 2018 15:53:52 +0200 Message-Id: <20180422135309.287086064@linuxfoundation.org> In-Reply-To: <20180422135304.577223025@linuxfoundation.org> References: <20180422135304.577223025@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 18db4b4e6fc31eda838dd1c1296d67dbcb3dc957 upstream. If some metadata block, such as an allocation bitmap, overlaps the superblock, it's very likely that if the file system is mounted read/write, the results will not be pretty. So disallow r/w mounts for file systems corrupted in this particular way. Backport notes: 3.18.y is missing bc98a42c1f7d ("VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)") and e462ec50cb5f ("VFS: Differentiate mount flags (MS_*) from internal superblock flags") so we simply use the sb MS_RDONLY check from pre bc98a42c1f7d in place of the sb_rdonly function used in the upstream variant of the patch. Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org Signed-off-by: Harsh Shandilya Signed-off-by: Greg Kroah-Hartman --- fs/ext4/super.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2131,6 +2131,8 @@ static int ext4_check_descriptors(struct ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Block bitmap for group %u overlaps " "superblock", i); + if (!(sb->s_flags & MS_RDONLY)) + return 0; } if (block_bitmap < first_block || block_bitmap > last_block) { ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " @@ -2143,6 +2145,8 @@ static int ext4_check_descriptors(struct ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Inode bitmap for group %u overlaps " "superblock", i); + if (!(sb->s_flags & MS_RDONLY)) + return 0; } if (inode_bitmap < first_block || inode_bitmap > last_block) { ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " @@ -2155,6 +2159,8 @@ static int ext4_check_descriptors(struct ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Inode table for group %u overlaps " "superblock", i); + if (!(sb->s_flags & MS_RDONLY)) + return 0; } if (inode_table < first_block || inode_table + sbi->s_itb_per_group - 1 > last_block) {