Formal models and scripts: bkd-write-niche-configs

Tools: Python

These are the working models and scripts this part of the hunt used. Some encode the code as it is (a counterexample is the expected result), others a fixed or correct variant; read the header comment of each file. Paths inside them were replaced by placeholders such as $LUCENE (a Lucene checkout) and $WORK.

Findings

• BKDWriter does not cap its in-heap point buffer at the Java array limit, so with maxMBSortInHeap >= 2048 MB a points merge of more than 2^31 bytes throws NegativeArraySizeException and closes the IndexWriter (finding LFV-613; repro · finding page)

Files

• bkd-heap-sort-buffer-int-overflow/model/alloc_overflow.py (used for LFV-613)

How to run

• Python: python3 <file>.py; scripts that import z3 need the z3-solver package.

Snapshot of 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.