nvmet-tcp: fix use-after-free when a port is removed

When removing a port, all its controllers are being removed, but there
are queues on the port that doesn't belong to any controller (during
connection time). This causes a use-after-free bug for any command
that dereferences req->port (like in nvmet_alloc_ctrl). Those queues
should be destroyed before freeing the port via configfs. Destroy
the remaining queues after the accept_work was cancelled guarantees
that no new queue will be created.
Signed-off-by: Israel Rukshin <israelr@nvidia.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/tcp.c

@@ -1737,6 +1737,17 @@ static int nvmet_tcp_add_port(struct nvmet_port *nport)
 	return ret;
 }
 
+static void nvmet_tcp_destroy_port_queues(struct nvmet_tcp_port *port)
+{
+	struct nvmet_tcp_queue *queue;
+
+	mutex_lock(&nvmet_tcp_queue_mutex);
+	list_for_each_entry(queue, &nvmet_tcp_queue_list, queue_list)
+		if (queue->port == port)
+			kernel_sock_shutdown(queue->sock, SHUT_RDWR);
+	mutex_unlock(&nvmet_tcp_queue_mutex);
+}
+
 static void nvmet_tcp_remove_port(struct nvmet_port *nport)
 {
 	struct nvmet_tcp_port *port = nport->priv;
@@ -1746,6 +1757,11 @@ static void nvmet_tcp_remove_port(struct nvmet_port *nport)
 	port->sock->sk->sk_user_data = NULL;
 	write_unlock_bh(&port->sock->sk->sk_callback_lock);
 	cancel_work_sync(&port->accept_work);
+	/*
+	 * Destroy the remaining queues, which are not belong to any
+	 * controller yet.
+	 */
+	nvmet_tcp_destroy_port_queues(port);
 
 	sock_release(port->sock);
 	kfree(port);