The Havoc Paradox in Generator-Based Fuzzing
Why this work is in the frame
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Bibliographic record
Abstract
Parametric generators combine coverage-guided and generator-based fuzzing for testing programs requiring structured inputs. They function as decoders that transform arbitrary byte sequences into structured inputs, allowing mutations on byte sequences to map directly to mutations on structured inputs, without requiring specialized mutators. However, this technique is prone to the havoc effect , where small mutations on the byte sequence cause large, destructive mutations to the structured input. This article investigates the paradoxical nature of the havoc effect for generator-based fuzzing in Java. In particular, we measure mutation characteristics and confirm the existence of the havoc effect, as well as scenarios where it may be more detrimental. Our evaluation across seven real-world Java applications compares various techniques that perform context-aware, finer-grained mutations on parametric byte sequences, such as JQF-EI, BeDivFuzz, and Zeugma. We find that these techniques exhibit better control over input mutations and consistently reduce the havoc effect compared to our coverage-guided fuzzer baseline Zest. While we find that context-aware mutation approaches can achieve significantly higher code coverage, we see that destructive mutations still play a valuable role in discovering inputs that increase code coverage. Specialized mutation strategies, while effective, impose substantial computational overhead—revealing practical tradeoffs in mitigating the havoc effect.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it