From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Alfie Cleveland <alfeh@me.com>
Date: Sun, 8 Jan 2017 04:31:36 +0000
Subject: [PATCH] Don't allow entities to ride themselves - #572


diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 83993fd6ea3702bb30d75f40e1a66f27ab2007b9..cd307f4eb94285c2687588ae53c1ed0382238332 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2241,6 +2241,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
     }
 
     protected boolean addPassenger(Entity entity) { // CraftBukkit
+        if (entity == this) throw new IllegalArgumentException("Entities cannot become a passenger of themselves"); // Paper - issue 572
         if (entity.getVehicle() != this) {
             throw new IllegalStateException("Use x.startRiding(y), not y.addPassenger(x)");
         } else {