BadgerDAO Zaps contest - ye0lde's results

Handle

ye0lde

Vulnerability details

Impact

Removing unused named return variables and local variables can reduce gas usage and improve code clarity.

Proof of Concept

calcMint, calcMintWithRen, calcMintWithWbtc Unused named returns https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L156

Unused local variables https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L178-L179 https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L197-L198

calcRedeem, calcRedeemInRen, calcRedeemInWbtc Unused named returns https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L251

Unused local variables https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L274-L275 https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L295-L296

Tools Used

Visual Studio Code, Remix

Recommended Mitigation Steps

Remove the unused named returns and local variables

Handle

ye0lde

Vulnerability details

Impact

Removing unneeded branches and returns can reduce gas usage and improve code clarity.

Proof of Concept

This code https://github.com/Badger-Finance/ibbtc/blob/d8b95e8d145eb196ba20033267a9ba43a17be02c/contracts/Zap.sol#L309-L317 can be refactored to:

	if (bBtc <= max) {
		// pesimistically charge 0.5% on the withdrawal.
		// Actual fee might be lesser if the vault keeps keeps a buffer
		uint strategyFee = sett.mul(controller.strategies(pool.lpToken).withdrawalFee()).div(10000);
		lp = sett.sub(strategyFee).mul(pool.sett.getPricePerFullShare()).div(1e18);
		fee = fee.add(strategyFee);
	}

Tools Used

Visual Studio Code, Remix

Recommended Mitigation Steps

See POC