ext4: disallow ea_inodes with extended attributes

An ea_inode stores the value of an extended attribute; it can not have
extended attributes itself, or this will cause recursive nightmares.
Add a check in ext4_iget() to make sure this is the case.

Cc: stable@kernel.org
Reported-by:  <syzbot+e44749b6ba4d0434cd47@syzkaller.appspotmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230524034951.779531-4-tytso@mit.edu


Signed-off-by: Theodore Ts'o <tytso@mit.edu>