Omniscia Kanpeki Finance Audit

Coordinator Manual Review Findings

Coordinator Manual Review Findings

COO-01M: Disjoint Settlement Action

Description:

The settlement of a forced liquidation is a secondary action that is reliant on the actual liquidation of the collateral that the administrator manages to achieve and can result in a desynchronized totalBorrowed state that can in-turn cause decreaseTokenTotalBorrowed to fail.

Example:

contracts/Coordinator.sol
140function decreaseTokenTotalBorrowed (address debtToken, uint256 amount) external override
141{
142  require(hasRole(UPDATER_ROLE, msg.sender), "!updater");
143

144

145  _asset[debtToken].totalBorrowed -= amount;
146}
147

148

149function increaseTokenCumulativeInterestPaid (address token, uint256 amount) external override
150{
151  require(hasRole(UPDATER_ROLE, msg.sender), "!updater");
152

153

154  _asset[token].cumulativeInterestPaid = _asset[token].cumulativeInterestPaid + amount;
155}
156

157

158function settleForcedLiquidation (address token, uint256 settledAmount, uint256 settledInterest) external onlyAdmin
159{
160  _vaultExists(token);
161

162

163  Asset memory asset = _asset[token];
164

165

166  _asset[token].totalBorrowed = asset.totalBorrowed - settledAmount;
167  // increase token cumulative interest paid
168  _asset[token].cumulativeInterestPaid = asset.cumulativeInterestPaid + settledInterest;
169

170

171  // settled amount: admin -> deposit vault
172  IERC20(token).safeTransferFrom(msg.sender, asset.vaults.deposit, settledAmount);
173  // settled interest: admin -> interest vault
174  IERC20(token).safeTransferFrom(msg.sender, asset.vaults.interest, settledInterest);
175

176

177  emit SettleForcedLiquidation(token, settledAmount, settledInterest);
178}

Recommendation:

We strongly recommend some form of validation to be imposed on the settledAmount to ensure that it is at most equal to the amount of the debt as any amount beyond that would cause the misbehaviour described. Alternatively, we advise the decreaseTokenTotalBorrowed function to reduce the totalBorrowed member by the minimum between totalBorrowed and amount to ensure it is operable at all times as it serves purely for statistical purposes.

Alleviation:

Our latter recommendation was applied whereby decrease total borrowed performs a minimum operation and can be executed under all circumstances.

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