Yield Witch v2 contest - ElKu's results

1) Bidding functions doesn't check if vault is still Undercollateralized

The bidding functions ( payBase and payFYToken ) should check if the vault is still Undercollateralized before proceeding with the Auction.

Currently, the auction can only be cancelled via the cancel function. This external function has to be called manually for checking if the vault is not Undercollateralized and cancel the auction.

Mitigation:

Make the cancel function public and call it from the two bidding functions.

2) Inconsistencies caused by updating Governance variables during an Ongoing Auction

The Governance variables such as lines, limit, auctioneerReward etc.. can be changed during an ongoing Auction. Even though this cannot be misused by a malicious user, it will cause inconsistencies in the calculation of variables like liquidatorCut and auctioneerCut (Calculated in _calcPayout function ).

Mitigation:

Store the line mapping and auctioneerReward in the Auction structure and use it in the bidding functions ( payBase and payFYToken ).

3) Spelling mistakes in natspec comments:

1. overriden
2. repayed
3. overriden
4. differente
5. overriden
6. quoutes hoy

Rearranging equation to save gas:

1. Equation uint256 inkAtEnd = uint256(artIn).wdiv(auction_.art).wmul(auction_.ink); can be rearranged as follows. Link

inkAtEnd = uint256(artIn).wdiv(auction_.art).wmul(auction_.ink)
         = (  ( (artIn * 1e18) / auction_.art ) * auction_.ink ) / 1e18;
         = (artIn * auction_.ink) / auction_.art;

There is no need to use WMul and Wdiv in this specific case.

So final equation will be:

uint256 inkAtEnd = (artIn * auction_.ink) / auction_.art;

2. Equation uint256(1e18 - initialProportion).wmul(elapsed.wdiv(duration)) can be rearranged as follows.

uint256(1e18 - initialProportion).wmul(elapsed.wdiv(duration))
         = ( uint256(1e18 - initialProportion) * ((elapsed * 1e18) / duration) ) / 1e18
         = ( uint256(1e18 - initialProportion) * elapsed) / duration

Since the above multiplication can never overflow we can safely put them in an unchecked block.

So 3 lines of equation here can be re-written as follows:

unchecked {
proportionNow =
                uint256(initialProportion) +
                ( uint256(1e18 - initialProportion) * elapsed) / duration
}

GAS Savings from the above Changes: