sctp: Prevent TOCTOU out-of-bounds write

In the Linux kernel, the following vulnerability has been resolved: sctp: Prevent TOCTOU out-of-bounds write For the following path not holding the sock lock, sctp_diag_dump() -> sctp_for_each_endpoint() -> sctp_ep_dump() make sure not to exceed bounds in case the address list has grown between buffer allocation (time-of-check) and write (time-of-use).