search

code-423n4 / 2021-12-vader-findings

0 stars 0 forks source link

Make use of a bitmap for claims to save gas in Converter.sol #48

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

Handle

TomFrenchBlockchain

Vulnerability details

Impact

Gas consumption

Proof of Concept

https://github.com/code-423n4/2021-12-vader/blob/fd2787013608438beae361ce1bb6d9ffba466c45/contracts/tokens/converter/Converter.sol#L50

Each claim performs a SSTORE to a fresh slot in order to mark a leaf as claimed. This results in each user paying 20k gas in order to invalidate a leaf whereas if many users shared the same slot they would pay 5k gas instead.

See Uniswap's implementation for inspiration:

https://github.com/Uniswap/merkle-distributor/blob/master/contracts/MerkleDistributor.sol

Recommended Mitigation Steps

Use bitmap for leaf invalidation