Paper/patches/server/0435-Prevent-position-desync-in-playerconnection-causing-.patch
Spottedleaf 41647af74c Do not use worldgen executor for api profile completions
We cannot put blocking network I/O onto the worldgen threads,
this will crash the server if it stalls
2022-07-03 14:55:56 -07:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Fri, 12 Jun 2020 16:51:39 -0700
Subject: [PATCH] Prevent position desync in playerconnection causing tp
exploit
Caused the server to revert to the player's overworld coordinates
after teleporting into the end.
Sidenote: The underlying issue is that the move call can teleport
entities and do other things like kill the entity. In the future,
to fix all exploits derieved from this usually unexpected
behaviour, we need to move all of this dangerous logic outside
of the move call and into an appropriate place in the tick method.
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 5157c257a3480b4f26d4a5830c36725af2d4bd4b..2daac5b9e7a9855a919024040bed4c065dce697a 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -1373,6 +1373,11 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Ser
this.player.move(MoverType.PLAYER, new Vec3(d7, d8, d9));
this.player.onGround = packet.isOnGround(); // CraftBukkit - SPIGOT-5810, SPIGOT-5835, SPIGOT-6828: reset by this.player.move
+ // Paper start - prevent position desync
+ if (this.awaitingPositionFromClient != null) {
+ return; // ... thanks Mojang for letting move calls teleport across dimensions.
+ }
+ // Paper end - prevent position desync
double d12 = d8;
d7 = d0 - this.player.getX();