Store hash of type(ZeroExStorage).creationCode rather than recalculating it on each call

[code423n4]

Handle

TomFrench

Vulnerability details

Impact

Deployment + runtime gas cost increase

Proof of Concept

On each time we calculate the address of ZeroExStorage we hash the entirety of the creation code for ZeroExStorage. This means that not only do we have to perform a large hash operation over the entire creation bytecode of this contract, we need to store all of this bytecode in the ZeroExOperator's deployed bytecode.

https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/operators/ZeroEx/ZeroExOperator.sol#L61

This hash could be calculated once at deployment and then have this used cheaply each time, reducing both deployment and runtime costs.

Recommended Mitigation Steps

Store keccak256(type(ZeroExStorage).creationCode) in an immutable (not constant as this still results in hashing being applied each time) variable.