fix(settlement): add cross-contract reentrancy guard (#8)#42
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elizabetheonoja-art merged 1 commit intoJun 25, 2026
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) Settlement entry points yield control to untrusted contracts at the cross-contract call boundary (oracle get_price_value, token transfer via collect_fee and the net transfer). A malicious token or oracle could re-enter settle/finalize_settlement before the first invocation completes and manipulate intermediate state. - Add DataKey::ReentrancyLock in storage.rs (temporary storage) - Add ReentrancyGuard RAII mutex in reentrancy.rs: acquire-before-call, release on Drop; strict (any re-entry panics with ReentrantCall). Panic path is covered by the host's storage revert (wasm uses panic=abort, so Drop does not run on unwind). - Acquire the guard at the top of settle() and finalize_settlement() - Add SettlementError::ReentrantCall - Tests: malicious-token reentry via settle and via finalize_settlement are both rejected; legitimate single settle still succeeds
elizabetheonoja-art
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Jun 25, 2026
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fix(settlement): cross-contract reentrancy guard
Closes #8
Solution
A strict RAII reentrancy mutex acquired before any external call and released on
scope exit.
storage.rs— newDataKey::ReentrancyLock, held in temporary storage.reentrancy.rs—ReentrancyGuard:new(&env)panics withSettlementError::ReentrantCallif the lock is alreadyheld, otherwise sets it (TTL 1 ledger).
Dropclears the lock on normal return.automatically — necessary because Wasm builds use
panic = "abort", whereDropdoes not run during unwinding.lib.rs—let _guard = ReentrancyGuard::new(&env);at the top ofsettleand
finalize_settlement; addedSettlementError::ReentrantCall = 4.Invariant: while any external call is in flight, the lock is set; any re-entry
into a guarded entry point aborts the transaction.
Files
contracts/settlement/src/storage.rs(new)contracts/settlement/src/reentrancy.rs(new)contracts/settlement/src/lib.rs(guards + error variant)contracts/settlement/src/test.rs(attack + regression tests)