lambdaclass / lambdaclass/lambda_compiler_kit
security: deep nesting causes stack overflow in JSON parser
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- Dominant language
- Lean
- Stars
- 2
- Forks
- 1
- PR merge metrics
- No merged PRs in 30d
Description
Problem
The JSON parser (parseValue/parseArrayElems/parseObjectElems) is mutually recursive with no depth limit. Deeply nested JSON (e.g., [[[[...10000 levels...]]]]) will exhaust the Lean runtime stack.
This is distinct from the DoS risk in #13 (which is about exponent arithmetic) — this is about recursion depth on the parse stack.
Expected fix
Add a configurable maximum nesting depth to the parser (defaulting to a safe value like 512 or 1024). Return a ParseError.nestingDepthExceeded on overflow.
References
- Related to: #13 (DoS prevention)
- Flagged by AI code review on PR #8
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 by reading the JSON parser functions parseValue, parseArrayElems, and parseObjectElems to trace their mutual recursion and existing ParseError handling. Define how the configurable depth limit is passed and what default is appropriate, then verify that deeply nested input returns ParseError.nestingDepthExceeded without exhausting the runtime stack.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers, security
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100