drivers/input/serio/i8042.c in the Linux kernel before 4.12.4 allows attackers to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact because the port->exists value can change after it is validated. It was discovered that a race condition existed in the i8042 serial device driver implementation in the Linux kernel. A physically proximate attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.