Nested Finance contest - defsec's results

C4-001 : Use of constant keccak variables results in extra hashing (and so gas)

Impact - Gas Optimization

That would Increase gas costs on all privileged operations.

Proof of Concept

1. Navigate to the following contract function and lines.

https://github.com/code-423n4/2022-02-nested/blob/main/contracts/abstracts/OwnableProxyDelegation.sol#L15

2. This results in the keccak operation being performed whenever the variable is used, increasing gas costs relative to just storing the output hash. Changing to immutable will only perform hashing on contract deployment which will save gas.

See: ethereum/solidity#9232 (https://github.com/ethereum/solidity/issues/9232#issuecomment-646131646)

Tools Used

Code Review

Recommended Mitigation Steps

Consider to change the variable to be immutable rather than constant.

C4-002 : Use of _msgSender()

Impact

The use of _msgSender() when there is no implementation of a meta transaction mechanism that uses it, such as EIP-2771, very slightly increases gas consumption.

Proof of Concept

_msgSender() is utilized three times where msg.sender could have been used in the following function.

https://github.com/code-423n4/2022-02-nested/blob/main/contracts/abstracts/OwnableProxyDelegation.sol#L40

Tools Used

None

Recommended Mitigation Steps

Replace _msgSender() with msg.sender if there is no mechanism to support meta-transactions like EIP-2771 implemented.

C4-003 : Immutable variables

Impact

'immutable' greatly reduces gas costs. There are variables that do not change so they can be marked as immutable to greatly improve the gas costs.

Proof of Concept

1. For instance : https://github.com/code-423n4/2022-02-nested/blob/main/contracts/abstracts/OwnableProxyDelegation.sol#L18

Tools Used

Code Review

Recommended Mitigation Steps

Mark variables as immutable.