4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Theodore Ts'o <tytso@xxxxxxx>
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 <tytso@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Harsh Shandilya <harsh@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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) {