Fuzz the runtime under fixed memory and step limits
Random bytecode tests occasionally hang or consume the test host, so the suite is disabled in continuous integration.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Fuzzing · Resource limits · Reproducibility
Estimated field mix
- Systems programming70%
- Quality engineering30%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional rules engine executes a tiny arithmetic bytecode over synthetic integers. Its interpreter trusts jump offsets and can run forever. Build a local Rust runtime; it has no filesystem, network, dynamic loading, host calls, or candidate-source execution.
Setup prerequisites
- Stacks
- Instruction decoding
- Control flow
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- SRUNTIME-101 · Decode instructions without reading past the bytecode buffer
- SRUNTIME-102 · Validate stack depth across both sides of a branch
- SRUNTIME-103 · Reject jumps that land inside instruction operands
- SRUNTIME-104 · Report integer overflow instead of changing arithmetic by build mode
- SRUNTIME-105 · Stop infinite programs with a deterministic instruction budget
- SRUNTIME-106 · Bound heap-like values without adding a garbage collector
- SRUNTIME-108 · Make runtime faults useful without leaking input values
Acceptance criteria
- Harness caps input bytes, instructions, value memory, and wall-clock defense
- Every failure records a minimized reproducible seed
- Crash, panic, timeout, and semantic disagreement are distinct outcomes
Implementation constraints
- Run only the capability-free local runtime; never execute generated host code.
Verification to include
- Replay the checked-in seed corpus with deterministic results.
- Seed malformed loops and oversized allocations and confirm bounded termination.
Deliverables
- Bounded fuzz harness and minimized regression corpus
Rollout and recovery
Start with a short deterministic CI corpus and schedule longer local runs separately.
Value of the work
For the engineer: Practice runtime invariants, validation, resource accounting and compatibility.
For the team: Review a constrained execution component whose malformed programs fail deterministically without gaining host capabilities.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.