In the Linux kernel 5.3.11, mounting a crafted btrfs image twice can cause an rwsem_down_write_slowpath use-after-free because (in rwsem_can_spin_on_owner in kernel/locking/rwsem.c) rwsem_owner_flags returns an already freed pointer,
https://usn.ubuntu.com/4414-1/
https://security.netapp.com/advisory/ntap-20200103-0001/
https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19318
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00021.html