Surround QueryParser.parse throws StackOverflowError instead of its declared ParseException on deeply nested groups (as few as about 740 levels, about 1.5 KB of query text, on a 1 MB thread stack)
Finding LFV-919Area: queryparser / surround (generated JavaCC parser, QueryParser.jj)Priority: lowImpact: wrong errorNovelty: new
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 the surround parser's documented entry point QueryParser.parse(String), which declares only ParseException and already turns the lexer's TokenMgrError (an Error) into a ParseException, on a valid query with many nested groups, for example "(".repeat(d) + "a" + ")".repeat(d) or a long chain of "(a OR " groups, and expect a query or a ParseException. Instead the generated recursive-descent grammar, which spends seven frames per "(" (FieldsQuery -> OrQuery -> AndQuery -> NotQuery -> NQuery -> WQuery -> PrimaryQuery -> FieldsQuery) and has no depth bound, runs out of stack and java.lang.StackOverflowError escapes parse, so a caller that handles ParseException gets an undeclared Error. On a 1 MB thread stack as few as about 740 nested groups (1,473 chars) are enough on the first deep parse, and an 800-term chain of parenthesised binary ORs (7,884 chars, under the module's 1024-basic-query limit) fails even after JIT warm-up.
The test shows that the surround QueryParser.parse on 100,000 nested parentheses lets StackOverflowError escape from its unbounded FieldsQuery -> ... -> PrimaryQuery recursion.
Expected vs actual
Expected: a query or the declared ParseException; actual: AssertionError: expected a query or ParseException, got StackOverflowError (-ea and -da).
Files
Run it
- Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
- Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
- Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
- 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=$CP:$LUCENE/lucene/facet/build/libs/lucene-facet-$V.jar
CP=$CP:$LUCENE/lucene/queries/build/libs/lucene-queries-$V.jar
CP=$CP:$LUCENE/lucene/queryparser/build/libs/lucene-queryparser-$V.jar
CP=$CP:$LUCENE/lucene/sandbox/build/libs/lucene-sandbox-$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" $(find src -name '*.java')
# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
-cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
execute --select-class org.apache.lucene.queryparser.surround.parser.TestSurroundDeepNestingThe module(s) facet also need their third-party runtime jars; ./gradlew -p lucene/<module> dependencies lists them.
Gradle 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 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.