The Linux kernel before 5.4.2 mishandles ext4_expand_extra_isize, as demonstrated by use-after-free errors in __ext4_expand_extra_isize and ext4_xattr_set_entry, related to fs/ext4/inode.c and fs/ext4/super.c, aka CID-4ea99936a163.
https://usn.ubuntu.com/4287-2/
https://usn.ubuntu.com/4287-1/
https://usn.ubuntu.com/4284-1/
https://usn.ubuntu.com/4258-1/
https://github.com/torvalds/linux/commit/4ea99936a1630f51fc3a2d61a58ec4a1c4b7d55a
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00021.html