Paper/patches/server/0938-Do-not-read-tile-entities-in-chunks-that-are-positio.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 18 Jun 2023 23:04:46 -0700
Subject: [PATCH] Do not read tile entities in chunks that are positioned
 outside of the chunk

The tile entities are not accessible and so should not be loaded.
This can happen as a result of users moving regionfiles around,
which would cause a crash on Folia but would appear to function
fine on Paper.

diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkSerializer.java b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkSerializer.java
index 3b046dc106b96b7ca2b148d605e8b7c97453d033..85de64c1e75e1323f8425fc53e525c215ff417ce 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkSerializer.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkSerializer.java
@@ -307,6 +307,13 @@ public class ChunkSerializer {
             for (int k1 = 0; k1 < nbttaglist3.size(); ++k1) {
                 CompoundTag nbttagcompound4 = nbttaglist3.getCompound(k1);
 
+                // Paper start - do not read tile entities positioned outside the chunk
+                BlockPos blockposition = BlockEntity.getPosFromTag(nbttagcompound4);
+                if ((blockposition.getX() >> 4) != chunkPos.x || (blockposition.getZ() >> 4) != chunkPos.z) {
+                    LOGGER.warn("Tile entity serialized in chunk " + chunkPos + " in world '" + world.getWorld().getName() + "' positioned at " + blockposition + " is located outside of the chunk");
+                    continue;
+                }
+                // Paper end - do not read tile entities positioned outside the chunk
                 ((ChunkAccess) object1).setBlockEntityNbt(nbttagcompound4);
             }
 
@@ -517,10 +524,19 @@ public class ChunkSerializer {
                     CompoundTag nbttagcompound1 = nbttaglist1.getCompound(i);
                     boolean flag = nbttagcompound1.getBoolean("keepPacked");
 
+                    // Paper start - do not read tile entities positioned outside the chunk
+                    BlockPos blockposition = BlockEntity.getPosFromTag(nbttagcompound1); // moved up
+                    ChunkPos chunkPos = chunk.getPos();
+                    if ((blockposition.getX() >> 4) != chunkPos.x || (blockposition.getZ() >> 4) != chunkPos.z) {
+                        LOGGER.warn("Tile entity serialized in chunk " + chunkPos + " in world '" + world.getWorld().getName() + "' positioned at " + blockposition + " is located outside of the chunk");
+                        continue;
+                    }
+                    // Paper end - do not read tile entities positioned outside the chunk
+
                     if (flag) {
                         chunk.setBlockEntityNbt(nbttagcompound1);
                     } else {
-                        BlockPos blockposition = BlockEntity.getPosFromTag(nbttagcompound1);
+                        // Paper - do not read tile entities positioned outside the chunk; move up
                         BlockEntity tileentity = BlockEntity.loadStatic(blockposition, chunk.getBlockState(blockposition), nbttagcompound1);
 
                         if (tileentity != null) {