Yield Witch v2 contest - hake's results

Low Risk Findings Overview

Non-critical Findings Overview

QA overview per contract

Low Risk Findings

[L-01] Missing address(0) check

Funds might be lost by accident if check is not implemented. 3 instances of this issue have been found:

[L-01] Witch.sol#L286-L301

    function payBase(
        bytes12 vaultId,
        address to,
        uint128 minInkOut,
        uint128 maxBaseIn
    )
        external
        returns (
            uint256 liquidatorCut,
            uint256 auctioneerCut,
            uint256 baseIn
        )
    {
        DataTypes.Auction memory auction_ = auctions[vaultId];
        require(auction_.start > 0, "Vault not under auction");

[L-01b] Witch.sol#L176-L177

    function auction(bytes12 vaultId, address to)

[L-01c] Witch.sol#L344-L359

    function payFYToken(
        bytes12 vaultId,
        address to,
        uint128 minInkOut,
        uint128 maxArtIn
    )
        external
        returns (
            uint256 liquidatorCut,
            uint256 auctioneerCut,
            uint256 artIn
        )
    {
        DataTypes.Auction memory auction_ = auctions[vaultId];
        require(auction_.start > 0, "Vault not under auction");

Non-critical Findings

[N-01] The use of magic numbers is not recommended

Consider setting constant numbers as a constant variable for better readability and clarity. 5 instances of this issue have been found:

[N-01] Witch.sol#L587-L588

            proportionNow = 1e18;

[N-01b] Witch.sol#L105-L106

            initialOffer == 0 || initialOffer >= 0.01e18,

[N-01c] Witch.sol#L108-L109

        require(proportion >= 0.01e18, "Proportion below 1%");

[N-01d] Witch.sol#L162-L163

        if (auctioneerReward_ > 1e18) {

[N-01e] Witch.sol#L591-L592

                uint256(1e18 - initialProportion).wmul(elapsed.wdiv(duration));

[N-02] Typo

Please fix typos. 2 instances of this issue have been found:

[N-02] Witch.sol#L81

/// @param param Name of parameter to set (must be "ladle")

[N-02b] Witch.sol#L14

uncollateralized -> undercollateralized

[N-03] Remove TODO’s

They add unnecessary cluttler and harm readbility for auditors. 1 instance of this issue has been found:

[N-03] Witch.sol#L577-L578

        // TODO: Replace this contract before then 😰 -> This is funny though

Gas Optimizations

Gas overview per contract

Gas Optimizations

[G-01] Multiple address mappings can be combined into a single mapping of an address to a struct, where appropriate

Saves a storage slot for the mapping. Depending on the circumstances and sizes of types, can avoid a Gsset (20000 gas) per mapping combined. Reads and subsequent writes can also be cheaper when a function requires both values and they both fit in the same storage slot. Finally, if both fields are accessed in the same function, can save ~42 gas per access due to not having to recalculate the key's keccak256 hash (Gkeccak256 - 30 gas) and that calculation's associated stack operatio 1 instance of this issue has been found:

[G-01] Witch.sol#L65-L69

    mapping(bytes12 => DataTypes.Auction) public auctions;
    mapping(bytes6 => mapping(bytes6 => DataTypes.Line)) public lines;
    mapping(bytes6 => mapping(bytes6 => DataTypes.Limits)) public limits;
    mapping(address => bool) public otherWitches;
    mapping(bytes6 => mapping(bytes6 => bool)) public ignoredPairs;

[G-02] require()/revert() checks used multiple times should be turned into a function or modifier

Doing so increases code readability decreases number of instructions for the compiler. 7 instances of this issue have been found:

[G-02] Witch.sol#L328-L329

            require(baseJoin != IJoin(address(0)), "Join not found");

[G-02b] Witch.sol#L365-L366

        require(liquidatorCut >= minInkOut, "Not enough bought");

[G-02c] Witch.sol#L313-L314

        require(liquidatorCut >= minInkOut, "Not enough bought");

[G-02d] Witch.sol#L416-L417

        require(auction_.start > 0, "Vault not under auction");

[G-02e] Witch.sol#L358-L359

        require(auction_.start > 0, "Vault not under auction");

[G-02f] Witch.sol#L300-L301

        require(auction_.start > 0, "Vault not under auction");

[G-02g] Witch.sol#L255-L256

        require(auction_.start > 0, "Vault not under auction");

[G-03] uints smaller than uint256 cost more gas

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size. Solidity docs 4 instances of this issue have been found:

[G-03] Witch.sol#L63

uint128 public auctioneerReward = 0.01e18;

[G-03b] Witch.sol#L232-L233

        uint128 art = uint256(balances.art).wmul(line.proportion).u128();

[G-03c] Witch.sol#L234-L235

        uint128 ink = (art == balances.art)

[G-03d] Witch.sol#L303-L304

        uint128 artIn = uint128(

[G-04] Use custom errors rather than revert()/require() strings to save gas

Custom errors save ~50 gas each time they're hit by avoiding having to allocate and store the revert string. 11 instances of this issue have been found:

[G-04] Witch.sol#L437-L440

               require(
                    auction_.art - artIn >= debt.min * (10**debt.dec),
                    "Leaves dust"
                );

[G-04b] Witch.sol#L416-L417

        require(auction_.start > 0, "Vault not under auction");

[G-04c] Witch.sol#L395-L396

            require(ilkJoin != IJoin(address(0)), "Join not found");

[G-04d] Witch.sol#L365-L366

        require(liquidatorCut >= minInkOut, "Not enough bought");

[G-04e] Witch.sol#L358-L359

        require(auction_.start > 0, "Vault not under auction");

[G-04f] Witch.sol#L328-L329

            require(baseJoin != IJoin(address(0)), "Join not found");

[G-04g] Witch.sol#L313-L314

        require(liquidatorCut >= minInkOut, "Not enough bought");

[G-04h] Witch.sol#L300-L301

        require(auction_.start > 0, "Vault not under auction");

[G-04i] Witch.sol#L102-L108

require(initialOffer <= 1e18, "InitialOffer above 100%");
        require(proportion <= 1e18, "Proportion above 100%");
        require(
            initialOffer == 0 || initialOffer >= 0.01e18,
            "InitialOffer below 1%"
        );
        require(proportion >= 0.01e18, "Proportion below 1%");

[G-04j] Witch.sol#L189-L190

        require(cauldron.level(vaultId) < 0, "Not undercollateralized");

[G-04k] Witch.sol#L200-L201

        require(limits_.sum <= limits_.max, "Collateral limit reached");