StoredFieldDataInput(ByteArrayDataInput) takes the input's end position as its length, so a ByteArrayDataInput that does not start at position 0 (a slice at a non-zero offset, or a partly read input) silently stores extra trailing bytes, or makes addDocument fail and close IndexWriter

Finding LFV-175Area: index / stored fields (StoredFieldDataInput: DataInput-backed StoredField values, #14213)Priority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-175

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

You add new StoredField(name, new StoredFieldDataInput(new ByteArrayDataInput(bytes, offset, len))) and expect the stored value to be exactly those len bytes, because the record's length is documented as 'the length of the data input'. The convenience constructor copies ByteArrayDataInput.length(), which is the end position offset + len, so for an 8-byte slice at offset 4 of a 16-byte array the document stores 12 bytes, the slice plus the next 4, with no error. If fewer bytes than the offset follow the slice, the stored fields writer reads past the array, addDocument throws ArrayIndexOutOfBoundsException and IndexWriter closes itself.

The test shows that StoredFieldDataInput(ByteArrayDataInput) uses the input's end position as its length, so a slice that does not start at 0 is stored with extra trailing bytes.

Expected vs actual

Expected: the stored value of new ByteArrayDataInput(buf16, 4, 8) is those 8 bytes buf[4..12); actual: 12 bytes buf[4..16), with -ea and -da.

Files

• src/org/apache/lucene/index/TestStoredFieldDataInputSlice.java (JUnit test)

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=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$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.index.TestStoredFieldDataInputSlice

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 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.