fs/f2fs/segment.c in the Linux kernel before 4.13 allows local users to cause a denial of service (NULL pointer dereference and panic) by using a noflush_merge option that triggers a NULL value for a flush_cmd_control data structure. It was discovered that the f2fs filesystem implementation in the Linux kernel did not handle the noflush_merge mount option correctly. An attacker could use this to cause a denial of service (system crash).