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Commit 6b06c4ae authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman
Browse files

ext4: Fix deadlock during directory rename 



[ 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: default avatar <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: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230301141004.15087-1-jack@suse.cz


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent a99a61d9

fs/ext4/namei.c

+17 −9
Original line number Diff line number Diff line
@@ -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 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry, 
	} 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;

}