A malicious caller can create a SocketAddress for a local unix socket with an
over-long name that does not fit into struct sock_addr_un.
- Socket::connet: This caused the 'sun_path' field to
overflow, probably overwriting the return pointer of the call frame, and thus
crashing the process (in the best case).
- SocketAddress::to_sockaddr_un: This triggered a RELEASE_ASSERT, and thus
crashing the process.
Both have been fixed to return a nice error code instead of crashing.
