An issue was discovered in fs/f2fs/super.c in the Linux kernel through 4.17.3. There is an out-of-bounds read or a divide-by-zero error for an incorrect user_block_count in a corrupted f2fs image, leading to a denial of service (BUG).
https://usn.ubuntu.com/4118-1/
https://usn.ubuntu.com/4094-1/
https://usn.ubuntu.com/3932-2/
https://usn.ubuntu.com/3932-1/
http://lists.opensuse.org/opensuse-security-announce/2018-10/msg00033.html