Description: dccp: check sk for closed state in dccp_sendmsg()
References:
 https://syzkaller.appspot.com/bug?id=833568de043e0909b2aeaef7be136db39d21ba94
 https://marc.info/?t=152036611500003&r=1&w=2
Notes:
Bugs:
upstream: released (4.16-rc7) [67f93df79aeefc3add4e4b31a752600f834236e2]
4.9-upstream-stable: released (4.9.92) [1fdc00c1503f2164893454958cf62c3bf4eff8d6]
3.16-upstream-stable: released (3.16.57) [e86c8c8cdf47ce06f29a080f9ab9ee8eee71b374]
3.2-upstream-stable: released (3.2.102) [109503b8cccb3b803d875b88d21d49eab921969e]
sid: released (4.15.17-1)
4.9-stretch-security: released (4.9.107-1)
3.16-jessie-security: released (3.16.57-1)
3.2-wheezy-security: released (3.2.102-1)