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Fix race condition on UpgradeData.BlockFixers class init

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The CHUNKY_FIXERS field is modified during the constructors
of the BlockFixers, but the code that uses CHUNKY_FIXERS does
not properly ensure that BlockFixers has been initialised before
using it, leading to a possible race condition where instances of
BlockFixers are accessed before they have initialised correctly.

We can force the class to initialise fully before accessing the
field by calling any method on the class, and for convenience
we use values().
This commit is contained in:
Spottedleaf 2023-08-08 17:29:33 -07:00
parent d12a537299
commit fa87f62891
1 changed files with 20 additions and 16 deletions
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36
paper-server/patches/sources/net/minecraft/world/level/chunk/UpgradeData.java.patch
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@ -1,13 +1,9 @@
--- a/net/minecraft/world/level/chunk/UpgradeData.java
+++ b/net/minecraft/world/level/chunk/UpgradeData.java
@@ -109,9 +109,28 @@
if (nbt.contains(key, 9)) {
for (Tag tag : nbt.getList(key, 10)) {
SavedTick.loadTick((CompoundTag)tag, nameToType).ifPresent(ticks::add);
+ }
+ }
+ }
+
@@ -113,12 +113,36 @@
}
}
+ // Paper start - filter out relocated neighbour ticks
+ // The lists are only supposed to contain ticks for the 1 radius neighbours of the chunk
+ private static <T> void filterTickList(int chunkX, int chunkZ, List<SavedTick<T>> ticks) {
@ -22,22 +18,30 @@
+ if (dist != 1) {
+ LOGGER.warn("Neighbour tick '" + tick + "' serialized in chunk (" + chunkX + "," + chunkZ + ") is too far (" + tickCX + "," + tickCZ + ")");
+ iterator.remove();
}
}
}
+ }
+ }
+ }
+ // Paper end - filter out relocated neighbour ticks
+
public void upgrade(LevelChunk chunk) {
this.upgradeInside(chunk);
@@ -120,6 +139,11 @@
for (Direction8 direction8 : DIRECTIONS) {
upgradeSides(chunk, direction8);
}
+
+ // Paper start - filter out relocated neighbour ticks
+ filterTickList(chunk.locX, chunk.locZ, this.neighborBlockTicks);
+ filterTickList(chunk.locX, chunk.locZ, this.neighborFluidTicks);
+ // Paper end - filter out relocated neighbour ticks
+
Level level = chunk.getLevel();
this.neighborBlockTicks.forEach(tick -> {
Block block = tick.type() == Blocks.AIR ? level.getBlockState(tick.pos()).getBlock() : tick.type();
@@ -129,6 +153,7 @@
Fluid fluid = tick.type() == Fluids.EMPTY ? level.getFluidState(tick.pos()).getType() : tick.type();
level.scheduleTick(tick.pos(), fluid, tick.delay(), tick.priority());
});
+ UpgradeData.BlockFixers.values(); // Paper - force the class init so that we don't access CHUNKY_FIXERS before all BlockFixers are initialised
CHUNKY_FIXERS.forEach(logic -> logic.processChunk(level));
}