Kernel: Hold socket back from accept() until it's fully set up

Author: https://github.com/deoxxa
Commit: 72f728b0d6
Pull-request: https://github.com/SerenityOS/serenity/pull/530
Reviewed-by: https://github.com/awesomekling

Kernel/Net/NetworkTask.cpp

@@ -459,6 +459,7 @@ void handle_tcp(const IPv4Packet& ipv4_packet)
                 socket->set_setup_state(Socket::SetupState::Completed);
                 socket->set_connected(true);
             }
+            socket->release_to_originator();
             return;
         default:
             kprintf("handle_tcp: unexpected flags in SynReceived state\n");