[mojo-edk] Sanity checks on ports message parsing

mojo/edk/system/node_controller.cc

Index: mojo/edk/system/node_controller.cc
diff --git a/mojo/edk/system/node_controller.cc b/mojo/edk/system/node_controller.cc
index 7c49bde1222188942e10f917e87bd9c31d318d62..888bf99882f5395bd9eec7ea51e56abaf1e92a86 100644
--- a/mojo/edk/system/node_controller.cc
+++ b/mojo/edk/system/node_controller.cc
@@ -790,20 +790,28 @@ void NodeController::OnAcceptBrokerClient(const ports::NodeName& from_node,
   DVLOG(1) << "Child " << name_ << " accepted by broker " << broker_name;
 }
 
-void NodeController::OnPortsMessage(Channel::MessagePtr channel_message) {
+void NodeController::OnPortsMessage(const ports::NodeName& from_node,
+                                    Channel::MessagePtr channel_message) {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
 
   void* data;
   size_t num_data_bytes;
   NodeChannel::GetPortsMessageData(
       channel_message.get(), &data, &num_data_bytes);
+  if (!num_data_bytes) {
+    DropPeer(from_node);
+    return;
+  }
 
   size_t num_header_bytes, num_payload_bytes, num_ports_bytes;
-  ports::Message::Parse(data,
-                        num_data_bytes,
-                        &num_header_bytes,
-                        &num_payload_bytes,
-                        &num_ports_bytes);
+  if (!ports::Message::Parse(data,
+                             num_data_bytes,
+                             &num_header_bytes,
+                             &num_payload_bytes,
+                             &num_ports_bytes)) {
+    DropPeer(from_node);
+    return;
+  }
 
   CHECK(channel_message);
   ports::ScopedMessage message(