ADR-172: wifi-densepose-cli + wifi-densepose-core CSI-Deserialiser Security Review

Field	Value
Status	Accepted — clean-with-evidence, 4 regression pins added
Date	2026-06-15
Deciders	ruv
Codename	CSI-DESERIALISER-HARDENING
Supersedes / amends	none (records review; references ADR-127 §9 for the core portion, ADR-136 for the pre-existing DoS ACs)

Context

The beyond-SOTA security sweep (branch feat/v2-beyond-sota-sweep) reviewed each v2/ crate for real, reproducible defects. Two crates had no prior dedicated security ADR:

• wifi-densepose-core — the dependency root for all 12 downstream crates (types, traits, error types, CSI frame primitives). A defect here is a force-multiplier: every consumer inherits it.
• wifi-densepose-cli — the user-facing entrypoint (calibrate/calibrate-serve/enroll/train-room/room-watch + MAT-gated), which parses untrusted UDP CSI packets and operator-supplied paths.

A specific hypothesis motivated the core review. Three earlier reviews in this campaign found a systemic NaN-state-poisoning bug class in crates that depend on core (wifi-densepose-calibration, -vitals, -geo): a non-finite (NaN/Inf) input latched into persistent filter/accumulator state (IIR y1/y2, running mean, Welford/von-Mises accumulator, voxel grid) → silent permanent feature failure. The load-bearing question for this review: does that bug class originate in a shared wifi-densepose-core primitive (making the right fix a single root fix), or was it independently re-implemented in each downstream crate (making the three existing local fixes complete)?

Decision

Record the review outcome and lock in the existing DoS guards with regression tests. No production code is changed — both crates were already hardened (ADR-136 acceptance criteria + sanitize_room_id); the gap was untested guards, which a future refactor could silently remove.

Load-bearing question — VERDICT: NO (the NaN class does not live in core)

wifi-densepose-core exposes no stateful accumulator of any kind — no Welford/running-mean, no von-Mises/circular-mean, no IIR/biquad filter state, no voxel grid.

• MEASURED: grep over core/src for welford|von_mises|biquad|y1|y2|running_mean|accumulat|voxel|self.*+= matched only the InvalidState error enum variant, "reset state" doc comments, and a test-only LCG — zero stateful logic. The only float math in core is construction-time projection (CsiFrame::new → amplitude/phase via mapv) and pure stateless utils functions; nothing persists across frames.
• Corroboration: wifi-densepose-calibration::Features::from_series (extract.rs:103–133) already filters non-finite samples → Features::ZERO. The downstream fixes are independently re-implemented, confirming each crate rolls its own accumulator and each local fix is correct and complete. A fix in core would be a no-op (there is nothing to fix).

Consequence: the NaN-state-poisoning class is a downstream-local pattern, not a core-rooted defect. No hidden fourth instance exists in the shared primitive.

Findings (all pins — guards already present, now tested)

#	Location	Guard (pre-existing)	Regression pin	Evidence (MEASURED)
1	core types.rs:801 from_canonical_bytes	saturating_mul shape-vs-length check before Vec::with_capacity(rows*cols)	canonical_decode_oversized_shape_is_bounded_not_allocated	With guard removed: panics capacity overflow at types.rs:801; with guard: passes
2	core types.rs decoder	typed CanonicalDecodeError, never panics	canonical_decode_never_panics_on_arbitrary_bytes (fuzz sweep)	panic-free on arbitrary bytes
3	cli calibrate.rs:276–291	length check buf.len() < 20 + n_pairs*2 before Array2::zeros(n_antennas*n_subcarriers)	test_parse_csi_packet_oversized_claim_is_rejected_not_allocated	255×65535 claim in a 2 KB packet → None (no allocation)
4	cli calibrate.rs parser	None-returning on malformed input	test_parse_csi_packet_never_panics_on_arbitrary_bytes (fuzz sweep)	panic-free on arbitrary UDP bytes

Dimensions confirmed clean (with evidence)

1. Panic-on-adversarial-input = 0 — from_canonical_bytes returns a typed error for every malformed class; parse_csi_packet returns None. Both fuzz-swept panic-free.
2. NaN handling — Confidence::new rejects NaN (!(0.0..=1.0).contains(&NaN) ⇒ Err); compute_bounding_box / to_flat_array are NaN-tolerant (f32 min/max ignore NaN).
3. Empty-frame safety — amplitude_variance / mean_amplitude are panic-free on an empty Array2 (ndarray 0.17 returns finite / None).
4. Unbounded-memory DoS — bounded in both deserialisers (findings 1 & 3).
5. Path traversal — calibrate-serve defends every client-supplied room_id/bank/baseline via sanitize_room_id ([A-Za-z0-9_-], 64-char cap) with existing tests; bearer-auth gate + non-loopback-bind warning present. mat export writes to an operator-supplied PathBuf (acceptable CLI behavior).
6. Secrets — --token is read from CALIBRATE_TOKEN env, never embedded.

Validation

• cargo test -p wifi-densepose-core → 35 → 37 lib passed, 0 failed (+3 doctests)
• cargo test -p wifi-densepose-cli --no-default-features → 24 → 26 passed, 0 failed
• cargo test --workspace --no-default-features → exit 0, 0 failed
• python archive/v1/data/proof/verify.py → VERDICT: PASS, hash f8e76f21a0f9852b70b6d9dd5318239f6b20cbcb4cdd995863263cecdc446f7a unchanged (core/cli are off the signal proof path — confirms no pipeline alteration)

Consequences

Positive

• Two CSI deserialisers (the untrusted-input boundary of both the library root and the network-facing CLI) now have their DoS guards pinned against regression — a future refactor that drops a length check fails CI.
• The NaN-state-poisoning class is settled as downstream-local; reviewers no longer need to suspect a shared-root defect, and the three prior local fixes are confirmed complete.

Negative

• None. Test-only change; no behavior or API change.

Neutral

• The core portion is also noted in ADR-127 §9 (shared security-review log); this ADR is the canonical record for the wifi-densepose-cli review.

Links

• ADR-127 — HOMECORE state machine (shared security-review log, §9)
• ADR-136 — pre-existing CSI deserialiser DoS acceptance criteria
• ADR-151 — per-room calibration (calibrate/calibrate-serve surfaces)