sctp: set sk_state back to CLOSED if autobind fails in sctp_listen_start
In the Linux kernel, the following vulnerability has been resolved:

sctp: set sk_state back to CLOSED if autobind fails in sctp_listen_start

In sctp_listen_start() invoked by sctp_inet_listen(), it should set the
sk_state back to CLOSED if sctp_autobind() fails due to whatever reason.

Otherwise, next time when calling sctp_inet_listen(), if sctp_sk(sk)->reuse
is already set via setsockopt(SCTP_REUSE_PORT), sctp_sk(sk)->bind_hash will
be dereferenced as sk_state is LISTENING, which causes a crash as bind_hash
is NULL.

  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  RIP: 0010:sctp_inet_listen+0x7f0/0xa20 net/sctp/socket.c:8617
  Call Trace:
   <TASK>
   __sys_listen_socket net/socket.c:1883 [inline]
   __sys_listen+0x1b7/0x230 net/socket.c:1894
   __do_sys_listen net/socket.c:1902 [inline]