Nibbl contest - sach1r0's results

Lack of zero-address check in the constructor

Details

Lack of zero-address checks may lead to infunctional protocol.

Mitigation

Consider adding zero-address checks such as: require(_vaultImplementation != address(0));

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L23-L27

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Some functions does not check for zero address

Details

It's important to check for zero-address to avoid redeploying of the contract when the address is accidentally set to zero-address.

Mitigation

Add a require statement, for example: require(_curator != address(0));

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L38-L56 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L64-L74 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L80-L86 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L88-L93 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L99-L102 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L123-L126 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L158-L161 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L173-L204 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L23-L25

Functions that are not called within the contract must set its visibility to external instead of public

Details

Setting function's visibility to external when it is only called externally can save gas because external function’s parameters are not copied into memory and are instead read from calldata directly. see reference: https://github.com/code-423n4/2021-06-gro-findings/issues/37

Mitigation

Set function visibility to external

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L64-L74 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L76-L78 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L80-L86 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L88-L93 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Twav/Twav.sol#L44-L46

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Using strict comparison operators can save gas

Details

In the EVM, there is no opcode for >= or <=. When using greater than or equal, two operations are performed: > and =. See reference: https://code4rena.com/reports/2022-04-backd/

Mitigation

I suggest changing require(basketUpdateTime != 0 && block.timestamp >= basketUpdateTime, "NibblVaultFactory: UPDATE_TIME has not passed"); to require(basketUpdateTime != 0 && block.timestamp > basketUpdateTime, "NibblVaultFactory: UPDATE_TIME has not passed"); as the difference in the comparison on the code is neglible.

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVaultFactory.sol#L107

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Solidity compiler will always read the length of the array during each iteration

Details

.length in a loop can be extracted into a variable and used where necessary to reduce the number of storage reads see reference: https://github.com/code-423n4/2021-10-union-findings/issues/92

Mitigation:

This extra costs can be avoided by caching the array length. Example: uint _assetAddressesLength = _assetAddresses.length; for (uint i = 0; i < _assetAddressesLength; ++i) { }

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L506 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L525 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L547 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L43 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L70 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L93

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No need to explicitly initialize variables with their default values

Details

When variables are not set, it is assumed to have it's default value(0 for uint, false for bool, address(0) for address). Explicitly initializing it with its default value is an anti-pattern and wastes gas.

Mitigation

change uint256 i = 0; to uint256 i; see reference: https://code4rena.com/reports/2022-02-jpyc/ [G-07] GENERAL RECOMMENDATIONS

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L506 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L525 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L547 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L43 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L70 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L93

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Pre-increment cost less gas than post-increment

Details

i++ costs more gas than ++i , for uint pre-decrement is cheaper than post-decrement see reference: https://github.com/code-423n4/2021-12-nftx-findings/issues/195

Mitigation

change i++ to ++i

Line of code

https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L506 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L525 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L547 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L43 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L70 https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L93