Backd Tokenomics contest - gzeon's results

Low

IERC20.approve might revert for some token

Some token return void in approve and will revert if the IERC20 interface is used. Consider using OZ's safeApprove https://github.com/code-423n4/2022-05-backd/blob/2a5664d35cde5b036074edef3c1369b984d10010/protocol/contracts/tokenomics/VestedEscrow.sol#L25-L26

        IERC20(rewardToken_).approve(msg.sender, type(uint256).max);

Hardcoded WETH address

WETH address might change if deployed on L2 https://github.com/code-423n4/2022-05-backd/blob/2a5664d35cde5b036074edef3c1369b984d10010/protocol/contracts/tokenomics/FeeBurner.sol#L25-L26

    address private constant _WETH = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2); // WETH

> 0 is less efficient than != 0 for uint in require condition

Ref: https://twitter.com/GalloDaSballo/status/1485430908165443590

protocol/contracts/tokenomics/AmmConvexGauge.sol:158:        require(amount > 0, Error.INVALID_AMOUNT);
protocol/contracts/tokenomics/AmmConvexGauge.sol:171:        require(amount > 0, Error.INVALID_AMOUNT);
protocol/contracts/tokenomics/VestedEscrow.sol:84:        require(unallocatedSupply > 0, "No reward tokens in contract");
protocol/contracts/tokenomics/KeeperGauge.sol:140:        require(totalClaimable > 0, Error.ZERO_TRANSFER_NOT_ALLOWED);
protocol/contracts/tokenomics/AmmGauge.sol:104:        require(amount > 0, Error.INVALID_AMOUNT);
protocol/contracts/tokenomics/AmmGauge.sol:125:        require(amount > 0, Error.INVALID_AMOUNT);

Float multiplication optimization

We can use the following function to save gas on float multiplications

// out = x * y unchecked{/} z
function fmul(uint256 x, uint256 y, uint256 z) internal pure returns(uint256 out){
assembly{
if iszero(eq(div(mul(x,y),x),y)) {revert(0,0)}
out := div(mul(x,y),z)
}
}

https://github.com/code-423n4/2022-05-backd/blob/2a5664d35cde5b036074edef3c1369b984d10010/protocol/contracts/tokenomics/VestedEscrow.sol#L156-L157

        return Math.min((locked * elapsed) / totalTime, locked);