glm-5.3-flash
a0dd3d2de4
The running validate_pair campaign found a third crash: in aligned mode a maxLength reservation (ADR-003 strategy 2, VARCHAR(N)) stores RAW zero-padded data with no length prefix — materialize and validate_bytes implement exactly that — but read_field read the entry through data_access::read_string, i.e. parsed the window's first four bytes as a u32 length prefix. Raw reservation bytes that look like a large prefix then fail bounds with Access while validate_bytes says Ok: the validate⇒read agreement lattice breaks on every aligned maxLength string/bytes field (any schema declaring maxLength in aligned mode). write_field had the same mismatch (prefix+data into a raw window). Engine fix: - VariableEncoding gains MaxLengthReserved (additive variant, ADR-003 strategy 2). OffsetMap::compute records it for maxLength fields with the default encoding; maxLength+offset-indirect stays OffsetIndirect (the pair read is intentional, the window reserves max_len bytes), preserving the W3-1 combination semantics. - read_field String/Bytes arms dispatch on MaxLengthReserved → new data_access::read_reservation_string / read_reservation (raw window inside-buffer check + NUL trim — the materializer's exact semantics). - write_field dispatches → new data_access::write_reservation (zero- pads the window, rejects oversized values with Access). - materialize_aligned reads MaxLengthReserved through the same new read_reservation paths (single source of truth; replaces the inline trim logic with an identical implementation). - offset_map compute rejects a MaxLengthReserved encoding reaching the walk with a clean Offset error (recorded, never declared). - builder round-trips: MaxLengthReserved serializes via maxLength (the document form), never as an encoding value. - three engine regression tests: raw-not-prefixed read, zero-pad write + oversize rejection, validate⇒read_field agreement. - fuzz/shared validate_pair invariant updated: the W3-1 shorter-than-reservation exemption now applies to offset-indirect only; reservations assert the full window in-bounds (fixed engine). - corpus regenerated for generator-consistent numbering (seeds 037-044 relabeled; W3-1/W3-2 artifacts remain 044/045-047 → now 044, 048-050 region) — 48 seeds, replay 30/30 green. Verification: main crate 573 tests pass; clippy -D warnings clean (crate + shared); wasm clean; cargo fuzz build clean.
alktype fuzzing
cargo-fuzz targets for the binary struct engine's untrusted-input
surfaces. The design and operating rules live in
docs/plans/fuzzing.md (adopted from alkhttp's
docs/plans/fuzzing.md; rationale in alkcall's
docs/research/fuzzing.md) — this README is the operational
cheat-sheet.
Layout
fuzz_targets/— nightly-onlyfuzz_target!binaries (thin wrappers).shared/— stable-toolchain library holding the invariant logic; the corpus replay tests run here on plaincargo test.corpus/<target>/— committed seeds (regenerate withpython3 fuzz/gen_fuzz_seeds.py).artifacts/— gitignored crash/oom/timeout artifacts + campaign logs.
Targets
| Target | Drives |
|---|---|
bast_compile |
AlkTypeEngine::compile in both layout modes over attacker-shaped BAST JSON (the whole schema side through one choke point) + validate_bast_doc + build_validator |
data_access |
the hand-rolled decode core (src/data_access.rs): fixed-width kinds, bool strictness, length-prefixed and indirect string/bytes, enums — over raw bytes with attacker-chosen offsets and endianness |
read_opseq |
the stateful SequentialReader (packed read side): op sequences (Next / NextBorrowed / Field / Reset / End) over hostile buffers under the compiled plan — cursor discipline, plan-order walks, the record-count spin bound, ADR-007 reader independence |
layout_build |
the packed write side (LayoutBuilder::build) with adversarial var_sizes over a five-schema menu — position disjointness/bounds, failed-write buffer-untouched contracts, write→read pair round trip |
Running a campaign — always detached
Agent sessions must never run fuzzing in the foreground (an OOM in a target can take down the session host; see docs/plans/fuzzing.md §2). Use the detached runner:
fuzz/run-detached.sh bast_compile
# poll:
tail -n 50 fuzz/artifacts/bast_compile-*.log
ls fuzz/artifacts/bast_compile/
pgrep -f "cargo fuzz run bast_compile"
FUZZ_RUNTIME_SECS=1800 fuzz/run-detached.sh bast_compile for a longer
campaign. The runner pins -fork=1 -rss_limit_mb=2048 -malloc_limit_mb=2048 -timeout=25 and detaches via setsid + nohup.
Corpus replay (the standing fuzz gate)
cargo test --manifest-path fuzz/shared/Cargo.toml
replays every committed seed through the same invariant functions the fuzz targets run — on stable, without nightly, no cargo-fuzz. Part of the release verification checklist (AGENTS.md).
Toolchain
fuzz/rust-toolchain.toml pins nightly (+ llvm-tools-preview) for
this subtree only; the main crate stays stable at MSRV 1.85. cargo fuzz build works from any CWD inside fuzz/ (rustup resolves the
toolchain per directory). Build:
cd fuzz && cargo fuzz build
# or from the repo root — the toolchain file is picked up by path:
cargo fuzz build -D