An issue was discovered in the Linux kernel 4.4.x before 4.4.195. There is a NULL pointer dereference in rds_tcp_kill_sock() in net/rds/tcp.c that will cause denial of service, aka CID-91573ae4aed0.
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.4.195
https://github.com/torvalds/linux/commit/91573ae4aed0a49660abdad4d42f2a0db995ee5e