python / python/library-fuzzers
`ast.py` harness accumulates immortal interned identifiers causing spurious OOMs
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- Dominant language
- Python
- Stars
- 5
- Forks
- 8
- PR merge metrics
- No merged PRs in 30d
Description
For example this testcase: https://oss-fuzz.com/testcase-detail/6425123073884160
As documented, these "live until interpreter shutdown." It also says that "the number of distinct identifiers and string constants is expected to stay low," but I guess they didn't account for fuzzing. I'm not quite sure how to periodically restart the fuzzer, without causing a hit.
(On the upside, this did technically find a CPython bug!)
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the ast.py harness and the linked OSS-Fuzz testcase, then read the referenced string interning documentation to understand the lifetime issue. Trace how the harness starts and maintains fuzzing runs, and determine how to avoid spurious OOMs without losing genuine findings such as the linked CPython bug.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- testing-qa
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 45/100