[MC-216588] Feature placement - java.lang.IllegalArgumentException: bound must be positive

The bug

Some features and decorators use Random.randInt with a configurable value as input. This input is not always validated to be above 0 and can crash the game.

Feature	Crashes if
`random_patch`	`xspread` < 0 or `yspread` < 0 or `zspread` < 0
`flower`	`xspread` <= 0 or `yspread` <= 0 or `zspread` <= 0
`random_patch` or `flower`	`block_placer.type` is `"column_placer"` and `block_placer.extra_size` < 0
`geode`	`min_distribution_points` >= `max_distribution_points` or `min_point_offset` >= `max_point_offset`
`simple_random_selector`	`features` is empty
`tree`	`foliage_placer.type` is `"pine_foliage_placer"` and calculated trunk height < `foliage_placer.height` [1]
Decorator
`depth_average`	`spread` < 0
`glowstone`	`count` < 0

How to reproduce

Download the attached data pack

[media]

and add it to a new world

Teleport to the mojira:crashland dimension

/execute in mojira:crashland run tp @s ~ ~ ~

❌ The game crashes
To test each of the above cases, open data/mojira/worldgen/biome/crashland.json and edit the configured feature on line 21.

Footnotes

Method and class names using Mojang names.

1. The reason only the PineFoliagePlacer can crash is because it uses nextInt in PineFoliagePlacer.foliageRadius. The value that is used for this is computed by trunkPlacer.getTreeHeight(...) - foliagePlacer.foliageHeight(...) + 1.

Attachments

crash-2021-02-23_01.12.56-server.txt

Crashland.zip

Comments 1

[Mod] markderickson 2021-02-23T00:46:46Z

I can confirm.