Bug fix: kickWithDeposit likely push LUP below HTP affecting healthy loans

src/libraries/external/KickerActions.sol

@@ -67,19 +67,6 @@ library KickerActions {
  uint256 kickPenalty; // [WAD] current debt added as kick penalty
  }
 
- /// @dev Struct used for `kickWithDeposit` function local vars.
- struct KickWithDepositLocalVars {
- uint256 amountToDebitFromDeposit; // [WAD] the amount of quote tokens used to kick and debited from lender deposit
- uint256 bucketCollateral; // [WAD] amount of collateral in bucket
- uint256 bucketDeposit; // [WAD] amount of quote tokens in bucket
- uint256 bucketLP; // [WAD] LP of the bucket
- uint256 bucketPrice; // [WAD] bucket price
- uint256 bucketScale; // [WAD] bucket scales
- uint256 bucketUnscaledDeposit; // [WAD] unscaled amount of quote tokens in bucket
- uint256 lenderLP; // [WAD] LP of lender in bucket
- uint256 redeemedLP; // [WAD] LP used by kick action
- }
-
  /**************/
  /*** Events ***/
  /**************/
@@ -101,7 +88,6 @@ library KickerActions {
  error InsufficientLP();
  error InvalidAmount();
  error NoReserves();
- error PriceBelowLUP();
  error ReserveAuctionTooSoon();
 
  /***************************/
@@ -160,115 +146,34 @@ library KickerActions {
  Bucket storage bucket = buckets_[index_];
  Lender storage lender = bucket.lenders[msg.sender];
 
- KickWithDepositLocalVars memory vars;
-
- if (bucket.bankruptcyTime < lender.depositTime) vars.lenderLP = lender.lps;
+ uint256 lenderLP = bucket.bankruptcyTime < lender.depositTime ? lender.lps : 0;
+ uint256 bucketDeposit = Deposits.valueAt(deposits_, index_);
 
- vars.bucketLP = bucket.lps;
- vars.bucketCollateral = bucket.collateral;
- vars.bucketPrice = _priceAt(index_);
- vars.bucketUnscaledDeposit = Deposits.unscaledValueAt(deposits_, index_);
- vars.bucketScale = Deposits.scale(deposits_, index_);
- vars.bucketDeposit = Maths.wmul(vars.bucketUnscaledDeposit, vars.bucketScale);
-
- // calculate amount to remove based on lender LP in bucket
- vars.amountToDebitFromDeposit = Buckets.lpToQuoteTokens(
- vars.bucketCollateral,
- vars.bucketLP,
- vars.bucketDeposit,
- vars.lenderLP,
- vars.bucketPrice,
+ // calculate amount lender is entitled in current bucket (based on lender LP in bucket)
+ uint256 entitledAmount = Buckets.lpToQuoteTokens(
+ bucket.collateral,
+ bucket.lps,
+ bucketDeposit,
+ lenderLP,
+ _priceAt(index_),
  Math.Rounding.Down
  );
 
- // cap the amount to remove at bucket deposit
- if (vars.amountToDebitFromDeposit > vars.bucketDeposit) vars.amountToDebitFromDeposit = vars.bucketDeposit;
+ // cap the amount entitled at bucket deposit
+ if (entitledAmount > bucketDeposit) entitledAmount = bucketDeposit;
 
- // revert if no amount that can be removed
- if (vars.amountToDebitFromDeposit == 0) revert InsufficientLiquidity();
+ // revert if no entitled amount
+ if (entitledAmount == 0) revert InsufficientLiquidity();
 
- // kick top borrower
+ // kick borrower
  kickResult_ = _kick(
  auctions_,
  deposits_,
  loans_,
  poolState_,
  Loans.getMax(loans_).borrower,
  limitIndex_,
- vars.amountToDebitFromDeposit
- );
-
- // amount to remove from deposit covers entire bond amount
- if (vars.amountToDebitFromDeposit > kickResult_.amountToCoverBond) {
- // cap amount to remove from deposit at amount to cover bond
- vars.amountToDebitFromDeposit = kickResult_.amountToCoverBond;
-
- // recalculate the LUP with the amount to cover bond
- kickResult_.lup = Deposits.getLup(deposits_, poolState_.debt + vars.amountToDebitFromDeposit);
- // entire bond is covered from deposit, no additional amount to be send by lender
- kickResult_.amountToCoverBond = 0;
- } else {
- // lender should send additional amount to cover bond
- kickResult_.amountToCoverBond -= vars.amountToDebitFromDeposit;
- }
-
- // revert if the bucket price used to kick and remove is below new LUP
- if (vars.bucketPrice < kickResult_.lup) revert PriceBelowLUP();
-
- // remove amount from deposits
- if (vars.amountToDebitFromDeposit == vars.bucketDeposit && vars.bucketCollateral == 0) {
- // In this case we are redeeming the entire bucket exactly, and need to ensure bucket LP are set to 0
- vars.redeemedLP = vars.bucketLP;
-
- Deposits.unscaledRemove(deposits_, index_, vars.bucketUnscaledDeposit);
- vars.bucketUnscaledDeposit = 0;
-
- } else {
- vars.redeemedLP = Buckets.quoteTokensToLP(
- vars.bucketCollateral,
- vars.bucketLP,
- vars.bucketDeposit,
- vars.amountToDebitFromDeposit,
- vars.bucketPrice,
- Math.Rounding.Up
- );
-
- uint256 unscaledAmountToRemove = Maths.floorWdiv(vars.amountToDebitFromDeposit, vars.bucketScale);
-
- // revert if calculated unscaled amount is 0
- if (unscaledAmountToRemove == 0) revert InsufficientLiquidity();
-
- Deposits.unscaledRemove(deposits_, index_, unscaledAmountToRemove);
- vars.bucketUnscaledDeposit -= unscaledAmountToRemove;
- }
-
- vars.redeemedLP = Maths.min(vars.lenderLP, vars.redeemedLP);
-
- // revert if LP redeemed amount to kick auction is 0
- if (vars.redeemedLP == 0) revert InsufficientLP();
-
- uint256 bucketRemainingLP = vars.bucketLP - vars.redeemedLP;
-
- if (vars.bucketCollateral == 0 && vars.bucketUnscaledDeposit == 0 && bucketRemainingLP != 0) {
- bucket.lps = 0;
- bucket.bankruptcyTime = block.timestamp;
-
- emit BucketBankruptcy(
- index_,
- bucketRemainingLP
- );
- } else {
- // update lender and bucket LP balances
- lender.lps -= vars.redeemedLP;
- bucket.lps -= vars.redeemedLP;
- }
-
- emit RemoveQuoteToken(
- msg.sender,
- index_,
- vars.amountToDebitFromDeposit,
- vars.redeemedLP,
- kickResult_.lup
+ entitledAmount
  );
  }