Mojo: Don't allow closed pipe handles to be sent

mojo/edk/system/ports/node.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/edk/system/ports/node.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 937 matching lines @@
   if (message->num_ports() > 0) {
     // Note: Another thread could be trying to send the same ports, so we need
     // to ensure that they are ours to send before we mutate their state.
 
     std::vector<scoped_refptr<Port>> ports;
     ports.resize(message->num_ports());
 
     {
       for (size_t i = 0; i < message->num_ports(); ++i) {
         ports[i] = GetPort_Locked(message->ports()[i]);
+        CHECK(ports[i]);
+
         ports[i]->lock.Acquire();
-
         int error = OK;
         if (ports[i]->state != Port::kReceiving)
           error = ERROR_PORT_STATE_UNEXPECTED;
         else if (message->ports()[i] == port->peer_port_name)
           error = ERROR_PORT_CANNOT_SEND_PEER;
 
         if (error != OK) {
           // Oops, we cannot send this port.
           for (size_t j = 0; j <= i; ++j)
             ports[i]->lock.Release();
@@ skipping 145 matching lines @@
 
   if (num_data_bytes)
     memcpy(header + 1, data, num_data_bytes);
 
   return message;
 }
 
 }  // namespace ports
 }  // namespace edk
 }  // namespace mojo