SimpleWKTShapeParser.parse throws StackOverflowError instead of a result or its declared ParseException when GEOMETRYCOLLECTIONs nest a few thousand levels deep, valid or unterminated (10,000 levels, about 210 KB of text, on the default thread stack of the test machine; every release since 7.6.0)
Finding LFV-954Area: core / geo WKT parsing (SimpleWKTShapeParser)Priority: lowImpact: wrong errorNovelty: known outside Lucene
AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.
What it shows
You call SimpleWKTShapeParser.parse on a GEOMETRYCOLLECTION that holds a GEOMETRYCOLLECTION, and so on 10,000 levels deep (about 210 KB of valid WKT), or on the same text left unterminated, and expect the nested Object[] result, or the method's declared ParseException for bad or too-deep input. Instead java.lang.StackOverflowError escapes, because parseGeometry and parseGeometryCollection call each other once per nesting level with no depth limit and nothing turns the Error into a ParseException; the same unterminated text still gives ParseException at 5,000 levels. The caller has no limit it can set, and a plain length cap does not help, because about 42 KB already fails on a 512 KiB stack while real polygons are often longer than 200 KB.
Expected vs actual
- Expected: The test passes: it asserts the documented behaviour.
- Actual: java.lang.StackOverflowError escapes, because parseGeometry and parseGeometryCollection call each other once per nesting level with no depth limit and nothing turns the Error into a ParseException; the same unterminated text still gives ParseException at 5,000 levels.
Files
Run it
- Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
- Tested on Lucene main a9779ef3c193 (2026-10-26): reproduced.
- How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
- Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.
# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar # JUnit Platform console launcher (Maven Central)
javac -d classes -cp "$CP" $(find src -name '*.java')
# run 1: assertions off (production-like), seed 383DEE9
java -da -dsa -Dtests.asserts=false --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=383DEE9 \
-cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
execute --select-class org.apache.lucene.geo.TestWKTDeepGeometryCollectionGradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).
Feedback
Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.
Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.