From: Theodore Ts'o Subject: [PATCH 2/2] ext4: don't allow r/w mounts if metadata blocks overlap the superblock Date: Mon, 26 Mar 2018 00:49:06 -0400 Message-ID: <20180326044906.13286-2-tytso@mit.edu> References: <20180326044906.13286-1-tytso@mit.edu> Cc: Theodore Ts'o , stable@vger.kernel.org To: Ext4 Developers List Return-path: In-Reply-To: <20180326044906.13286-1-tytso@mit.edu> Sender: stable-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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. Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org --- fs/ext4/super.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7cd022c344d1..edcfe6956eba 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2335,6 +2335,8 @@ static int ext4_check_descriptors(struct super_block *sb, ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Block bitmap for group %u overlaps " "superblock", i); + if (!sb_rdonly(sb)) + return 0; } if (block_bitmap < first_block || block_bitmap > last_block) { ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " @@ -2347,6 +2349,8 @@ static int ext4_check_descriptors(struct super_block *sb, ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Inode bitmap for group %u overlaps " "superblock", i); + if (!sb_rdonly(sb)) + return 0; } if (inode_bitmap < first_block || inode_bitmap > last_block) { ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " @@ -2359,6 +2363,8 @@ static int ext4_check_descriptors(struct super_block *sb, ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: " "Inode table for group %u overlaps " "superblock", i); + if (!sb_rdonly(sb)) + return 0; } if (inode_table < first_block || inode_table + sbi->s_itb_per_group - 1 > last_block) { -- 2.16.1.72.g5be1f00a9a