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ext4: Fix deadlock during directory rename

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[ Upstream commit 3c92792da8506a295afb6d032b4476e46f979725 ]

As lockdep properly warns, we should not be locking i_rwsem while having
transactions started as the proper lock ordering used by all directory
handling operations is i_rwsem -> transaction start. Fix the lock
ordering by moving the locking of the directory earlier in
ext4_rename().

Reported-by: syzbot+9d16c39efb5fade84574@syzkaller.appspotmail.com
Fixes: 0813299c586b ("ext4: Fix possible corruption when moving a directory")
Link: https://syzkaller.appspot.com/bug?extid=9d16c39efb5fade84574
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230301141004.15087-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jan Kara 2023-03-01 15:10:04 +01:00 committed by Greg Kroah-Hartman
parent a99a61d9e1
commit 6b06c4ae64
1 changed files with 17 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
fs/ext4/namei.c
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@ -3795,10 +3795,20 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
return retval;
}
/*
* We need to protect against old.inode directory getting converted
* from inline directory format into a normal one.
*/
if (S_ISDIR(old.inode->i_mode))
inode_lock_nested(old.inode, I_MUTEX_NONDIR2);
old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de,
&old.inlined);
if (IS_ERR(old.bh))
return PTR_ERR(old.bh);
if (IS_ERR(old.bh)) {
retval = PTR_ERR(old.bh);
goto unlock_moved_dir;
}
/*
* Check for inode number is _not_ due to possible IO errors.
* We might rmdir the source, keep it as pwd of some process
@ -3855,11 +3865,6 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
if (new.dir != old.dir && EXT4_DIR_LINK_MAX(new.dir))
goto end_rename;
}
/*
* We need to protect against old.inode directory getting
* converted from inline directory format into a normal one.
*/
inode_lock_nested(old.inode, I_MUTEX_NONDIR2);
retval = ext4_rename_dir_prepare(handle, &old);
if (retval) {
inode_unlock(old.inode);
@ -3960,12 +3965,15 @@ end_rename:
} else {
ext4_journal_stop(handle);
}
if (old.dir_bh)
inode_unlock(old.inode);
release_bh:
brelse(old.dir_bh);
brelse(old.bh);
brelse(new.bh);
unlock_moved_dir:
if (S_ISDIR(old.inode->i_mode))
inode_unlock(old.inode);
return retval;
}