Joyn contest - Tomio's results

1. !=0 more effective than < 0

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreCollection.sol#L146 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreCollection.sol#L161 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L74-L77

Recommended Mitigation Steps: Change > 0 or < 0 to != 0

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2. unnecessary value set. the default value of uint is zero.

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L267 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L98 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreCollection.sol#L279

Recommended Mitigation Steps: remove 0

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3. using ++i can save gas

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreCollection.sol#L279 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L79 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L98

Recommended Mitigation Steps: change i++ to ++i

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4. Using < is cheaper than <=

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreCollection.sol#L147-L150

Recommended Mitigation Steps: Change from <= to <

require(
            totalSupply() + amount < maxSupply,
            "CoreCollection: Over Max Supply"
        );

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5. Caching .length for loop

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L79 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L98 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L147 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/MultiSigWallet.sol#L268

Recommended Mitigation Steps:

uint256 newVar = _collections.length;
for (uint256 i; i < newVar; i++)

by caching _collections.length to newVar can save gas

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6. the best way to use SafeERC20.function for gas opt

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreMultiSig.sol#L10

Recommended Mitigation Steps: by not declaring:

using SafeERC20 for IERC20;

and use:

SafeERC20.safeTransfer(IERC20(token), to, amount);

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7. Using == true cost more gas

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/royalty-vault/contracts/RoyaltyVault.sol#L43-L57

Recommended Mitigation Steps: Using == true to validate bool variable is unnecessary:

require(
            IERC20(royaltyAsset).transfer(splitterProxy, splitterShare),
            "Failed to transfer royalty Asset to splitter"
        );

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8. Using calldata to store struct data type can save gas

Proof of Concept: https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L72 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L80 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L110 https://github.com/code-423n4/2022-03-joyn/blob/main/core-contracts/contracts/CoreFactory.sol#L142

Recommended Mitigation Steps: Change to:

Collection[] calldata _collections

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