From ac65d6fee722653f8d1d0957bb88b250bb32c4e7 Mon Sep 17 00:00:00 2001
From: Zach Brown <zach.brown@destroystokyo.com>
Date: Sat, 12 Nov 2016 23:25:22 -0600
Subject: [PATCH] Filter bad data from ArmorStand and SpawnEgg items


diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index 656ecdacaf..2c7e6de02f 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -3,6 +3,7 @@ package com.destroystokyo.paper;
 import java.util.List;
 
 import net.minecraft.server.MinecraftServer;
+import org.bukkit.Bukkit;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.spigotmc.SpigotWorldConfig;
 
@@ -334,4 +335,12 @@ public class PaperWorldConfig {
     private void removeCorruptTEs() {
         removeCorruptTEs = getBoolean("remove-corrupt-tile-entities", false);
     }
+
+    public boolean filterNBTFromSpawnEgg = true;
+    private void fitlerNBTFromSpawnEgg() {
+        filterNBTFromSpawnEgg = getBoolean("filter-nbt-data-from-spawn-eggs-and-related", true);
+        if (!filterNBTFromSpawnEgg) {
+            Bukkit.getLogger().warning("Spawn Egg and Armor Stand NBT filtering disabled, this is a potential security risk");
+        }
+    }
 }
diff --git a/src/main/java/net/minecraft/server/EntityFallingBlock.java b/src/main/java/net/minecraft/server/EntityFallingBlock.java
index 1fb912eb0d..3c3f82f987 100644
--- a/src/main/java/net/minecraft/server/EntityFallingBlock.java
+++ b/src/main/java/net/minecraft/server/EntityFallingBlock.java
@@ -228,6 +228,15 @@ public class EntityFallingBlock extends Entity {
 
     protected void a(NBTTagCompound nbttagcompound) {
         this.block = GameProfileSerializer.d(nbttagcompound.getCompound("BlockState"));
+
+        // Paper start - Block FallingBlocks with Command Blocks
+        // Check mappings on update - dc = "repeating_command_block" - dd = "chain_command_block"
+        final Block b = this.block.getBlock();
+        if (this.world.paperConfig.filterNBTFromSpawnEgg && (b == Blocks.COMMAND_BLOCK || b == Blocks.REPEATING_COMMAND_BLOCK || b == Blocks.CHAIN_COMMAND_BLOCK)) {
+            this.block = Blocks.STONE.getBlockData();
+        }
+        // Paper end
+
         this.ticksLived = nbttagcompound.getInt("Time");
         if (nbttagcompound.hasKeyOfType("HurtEntities", 99)) {
             this.hurtEntities = nbttagcompound.getBoolean("HurtEntities");
-- 
2.19.0