Paper/patches/server/0674-Only-write-chunk-data-to-disk-if-it-serializes-witho.patch
Owen 89d51d5f29
Allow enabling sand duping (#10191)
Because this exploit has been widely known for years and has not been fixed by Mojang, we decided that it was worth allowing people to toggle it on/off due to how easy it is to make it configurable.

It should be noted that this decision does not promise all future exploits will be configurable.
2024-03-03 17:05:34 -05:00

95 lines
4.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 19 Dec 2021 09:13:41 -0800
Subject: [PATCH] Only write chunk data to disk if it serializes without
throwing
This ensures at least a valid version of the chunk exists
on disk, even if outdated
diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
index 140d6e455c1729f6e31e95facba5520b75ad838c..169e375c814ff814d15101d09dccc67783f50465 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
@@ -420,6 +420,7 @@ public class RegionFile implements AutoCloseable {
}
+ public static final int MAX_CHUNK_SIZE = 500 * 1024 * 1024; // Paper - don't write garbage data to disk if writing serialization fails
private class ChunkBuffer extends ByteArrayOutputStream {
private final ChunkPos pos;
@@ -433,6 +434,23 @@ public class RegionFile implements AutoCloseable {
super.write(RegionFile.this.version.getId());
this.pos = chunkcoordintpair;
}
+ // Paper start - don't write garbage data to disk if writing serialization fails
+ @Override
+ public void write(final int b) {
+ if (this.count > MAX_CHUNK_SIZE) {
+ throw new RegionFileStorage.RegionFileSizeException("Region file too large: " + this.count);
+ }
+ super.write(b);
+ }
+
+ @Override
+ public void write(final byte[] b, final int off, final int len) {
+ if (this.count + len > MAX_CHUNK_SIZE) {
+ throw new RegionFileStorage.RegionFileSizeException("Region file too large: " + (this.count + len));
+ }
+ super.write(b, off, len);
+ }
+ // Paper end - don't write garbage data to disk if writing serialization fails
public void close() throws IOException {
ByteBuffer bytebuffer = ByteBuffer.wrap(this.buf, 0, this.count);
diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
index b5b7b73048eaadfe58961631427da7574d42f5e8..fa086a19f038b929f356292b2f657929765f7b6f 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
@@ -145,10 +145,17 @@ public class RegionFileStorage implements AutoCloseable {
try {
NbtIo.write(nbt, (DataOutput) dataoutputstream);
+ // Paper start - don't write garbage data to disk if writing serialization fails
+ dataoutputstream.close(); // Only write if successful
+ } catch (final RegionFileSizeException e) {
+ attempts = 5; // Don't retry
+ regionfile.clear(pos);
+ throw e;
+ // Paper end - don't write garbage data to disk if writing serialization fails
} catch (Throwable throwable) {
if (dataoutputstream != null) {
try {
- dataoutputstream.close();
+ //dataoutputstream.close(); // Paper - don't write garbage data to disk if writing serialization fails
} catch (Throwable throwable1) {
throwable.addSuppressed(throwable1);
}
@@ -156,10 +163,7 @@ public class RegionFileStorage implements AutoCloseable {
throw throwable;
}
-
- if (dataoutputstream != null) {
- dataoutputstream.close();
- }
+ // Paper - don't write garbage data to disk if writing serialization fails; move into try block to only write if successfully serialized
}
// Paper start - Chunk save reattempt
return;
@@ -202,4 +206,13 @@ public class RegionFileStorage implements AutoCloseable {
}
}
+
+ // Paper start - don't write garbage data to disk if writing serialization fails
+ public static final class RegionFileSizeException extends RuntimeException {
+
+ public RegionFileSizeException(String message) {
+ super(message);
+ }
+ }
+ // Paper end - don't write garbage data to disk if writing serialization fails
}