Two resource-exhaustion fixes from Opus Rust + Sonnet Rust audits.
1. kei-cortex per_user_locks DashMap unbounded growth (HIGH)
File: kei-cortex/src/state.rs
Bug: per_user_locks: DashMap<String, Arc<Mutex<()>>> inserted on every
distinct user_id; never evicted. Auth'd attacker with 1M unique user_ids
could OOM the daemon (~150 bytes/entry = 15GB at 100M entries).
Fix: replaced DashMap with tokio::sync::Mutex<LruCache<String,
Arc<TokioMutex<()>>>> capped at PER_USER_LOCK_CAP = 1024. Eviction is
safe because callers hold their own Arc clone for their critical section;
dropping the registry slot retires only the registry's reference. Used
tokio::sync::Mutex for the registry because LruCache::get mutates the
recency list and requires &mut self.
Constructor Pattern: state.rs split into state.rs (184 LOC) +
state_factories.rs (64 LOC, new). Tests added: user_lock_evicts_past_cap
(registry stays ≤1024 after 2048 inserts), user_lock_keeps_most_recent
(LRU recency preserved). Existing user_lock_is_stable_per_user +
user_lock_differs_per_user updated to async — sole call site
(handlers/portrait.rs) gains .await.
2. kei-runtime stdout/stderr cap was post-hoc (HIGH)
File: kei-runtime/src/invoke.rs
Bug: wait_with_output() buffered ALL child stdout/stderr; only cap_bytes
truncated AFTER the child finished. A malicious atom writing 10 GB stdout
(or a buggy one looping infinitely) OOM'd the runtime BEFORE the cap fired.
Fix: replaced wait_with_output() with two reader threads sharing
KillHandle = Arc<Mutex<Option<Child>>>. Each reader appends bytes up to
STREAM_CAP = 16 MiB; on cap exceedance the reader KILLS the child from
inside the reader thread (critical — otherwise the unbounded writer would
never EOF and a post-hoc kill would never fire). Both readers drain the
closing pipe to EOF and return. Truncation surfaces as
InvokeError::SubprocessError with explicit "exceeded N byte cap" message.
Constructor Pattern: invoke.rs decomposed into invoke.rs (159 LOC) +
invoke_io.rs (146 LOC, new) + invoke_error.rs (54 LOC, new). Test added:
invoke_kills_runaway_atom — stages a kei-flood script running cat
/dev/zero, verifies (a) non-zero exit, (b) stdout < 18 MiB, (c)
"cap"/"subprocess" in stderr.
cargo check --workspace: clean. cargo test -p kei-cortex -p kei-runtime
--test-threads=1: 471 pass / 0 fail. Pre-existing openai_loop_wiring.rs
parallel-run flake (state collision when test-threads>1) is unrelated and
unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
