[LUCENE-8221] MoreLikeThis.setMaxDocFreqPct can easily int-overflow on larger indexes

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 7.4
• Lucene Fields: New
• Assignee: Dawid Weiss
• Reporter: Dawid Weiss
• Created: 26/Mar/18 06:54
• Updated: 27/Jun/18 08:30
• Resolved: 25/May/18 10:23

Description

  public void setMaxDocFreqPct(int maxPercentage) {
    this.maxDocFreq = maxPercentage * ir.numDocs() / 100;
  }

The above overflows integer range into negative numbers on even fairly small indexes (for maxPercentage = 75, it happens for just over 28 million documents.

We should make the computations on long range so that it doesn't overflow and have a more strict argument validation.

Issue Links

• is related to: LUCENE-8333 Switch MoreLikeThis.setMaxDocFreqPct to use maxDoc instead of numDocs