PaperMC/Spigot-Server-Patches/0500-Prevent-position-desync-in-playerconnection-causing-.patch
Shane Freeder 7ef05fbd8a Do not perform neighbour updates when using debug stick (Fixes #2134)
CB blindly drops any update flags when recording block modifications,
this causes the debug stick to blindly update neighbouring blocks on usage
in order to control this, we will special case this item, however, this
ideally should be fixed by recording the actual update flags used,
but will induce ABI breaks...

This patch also maintains the behavior of the BlockPlaceEvent, this
behavior will NOT be guaranteed in the future, however.
2020-12-22 22:45:10 +00:00

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1.8 KiB
Diff

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/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index e76c01a33bfcee1a9d312247b8d08026055204c8..45379bf4903ca8044145504207acd59c221b7f26 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -1176,6 +1176,11 @@ public class PlayerConnection implements PacketListenerPlayIn {
this.player.move(EnumMoveType.PLAYER, new Vec3D(d7, d8, d9));
this.player.setOnGround(packetplayinflying.b()); // CraftBukkit - SPIGOT-5810, SPIGOT-5835: reset by this.player.move
+ // Paper start - prevent position desync
+ if (this.teleportPos != null) {
+ return; // ... thanks Mojang for letting move calls teleport across dimensions.
+ }
+ // Paper end - prevent position desync
double d12 = d8;
d7 = d4 - this.player.locX();