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89d51d5f29
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.
92 lines
4.2 KiB
Diff
92 lines
4.2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Aikar <aikar@aikar.co>
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Date: Fri, 29 May 2020 20:29:02 -0400
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Subject: [PATCH] Synchronize PalettedContainer instead of
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ThreadingDetector/Semaphore
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Mojang has flaws in their logic about chunks being concurrently
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wrote to. So we constantly see crashes around multiple threads writing.
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Additionally, java has optimized synchronization so well that its
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in many times faster than trying to manage read write locks for low
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contention situations.
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And this is extremely a low contention situation.
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diff --git a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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index b8fb6d1d85e07f5165bfaf7d80807e069b595851..dd62e257e16974a6d556a7f5e2d113a2cbc08981 100644
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--- a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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+++ b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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@@ -32,14 +32,14 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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public final IdMap<T> registry;
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private volatile PalettedContainer.Data<T> data;
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private final PalettedContainer.Strategy strategy;
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- private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer");
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+ // private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer"); // Paper - unused
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public void acquire() {
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- this.threadingDetector.checkAndLock();
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+ // this.threadingDetector.checkAndLock(); // Paper - disable this - use proper synchronization
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}
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public void release() {
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- this.threadingDetector.checkAndUnlock();
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+ // this.threadingDetector.checkAndUnlock(); // Paper - disable this
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}
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public static <T> Codec<PalettedContainer<T>> codecRW(IdMap<T> idList, Codec<T> entryCodec, PalettedContainer.Strategy paletteProvider, T defaultValue) {
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@@ -91,7 +91,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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@Override
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- public int onResize(int newBits, T object) {
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+ public synchronized int onResize(int newBits, T object) { // Paper - synchronize
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PalettedContainer.Data<T> data = this.data;
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PalettedContainer.Data<T> data2 = this.createOrReuseData(data, newBits);
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data2.copyFrom(data.palette, data.storage);
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@@ -116,7 +116,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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return this.getAndSet(this.strategy.getIndex(x, y, z), value);
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}
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- private T getAndSet(int index, T value) {
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+ private synchronized T getAndSet(int index, T value) { // Paper - synchronize
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int i = this.data.palette.idFor(value);
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int j = this.data.storage.getAndSet(index, i);
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return this.data.palette.valueFor(j);
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@@ -133,7 +133,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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- private void set(int index, T value) {
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+ private synchronized void set(int index, T value) { // Paper - synchronize
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int i = this.data.palette.idFor(value);
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this.data.storage.set(index, i);
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}
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@@ -158,7 +158,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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});
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}
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- public void read(FriendlyByteBuf buf) {
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+ public synchronized void read(FriendlyByteBuf buf) { // Paper - synchronize
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this.acquire();
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try {
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@@ -174,7 +174,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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@Override
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- public void write(FriendlyByteBuf buf) {
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+ public synchronized void write(FriendlyByteBuf buf) { // Paper - synchronize
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this.acquire();
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try {
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@@ -229,7 +229,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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@Override
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- public PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) {
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+ public synchronized PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) { // Paper - synchronize
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this.acquire();
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PalettedContainerRO.PackedData var12;
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