Summary
distributeAssets function carried out multiplication on result of division that cause larger precision error leading to loss of rewards.
Vulnerability Details
The distributeAssets function have variables _portion and costInEuros at line 219 and 220 respectivley.
_portion variable save value as a result from division on line 219, which is later used in two more calculation at line 220 on uint256 costInEuros var. The costInEuros carried out multiplication on result of _portion that result in rounding down issue.
function distributeAssets(ILiquidationPoolManager.Asset[] memory _assets, uint256 _collateralRate, uint256 _hundredPC) external payable {
consolidatePendingStakes();
(,int256 priceEurUsd,,,) = Chainlink.AggregatorV3Interface(eurUsd).latestRoundData();
uint256 stakeTotal = getStakeTotal();
uint256 burnEuros;
uint256 nativePurchased;
for (uint256 j = 0; j < holders.length; j++) {
Position memory _position = positions[holders[j]];
uint256 _positionStake = stake(_position);
if (_positionStake > 0) {
for (uint256 i = 0; i < _assets.length; i++) {
ILiquidationPoolManager.Asset memory asset = _assets[i];
if (asset.amount > 0) {
(,int256 assetPriceUsd,,,) = Chainlink.AggregatorV3Interface(asset.token.clAddr).latestRoundData();
uint256 _portion = asset.amount * _positionStake / stakeTotal;
uint256 costInEuros = _portion * 10 ** (18 - asset.token.dec) * uint256(assetPriceUsd) / uint256(priceEurUsd)
* _hundredPC / _collateralRate;
if (costInEuros > _position.EUROs) {
_portion = _portion * _position.EUROs / costInEuros;
costInEuros = _position.EUROs;
}
_position.EUROs -= costInEuros;
rewards[abi.encodePacked(_position.holder, asset.token.symbol)] += _portion;
burnEuros += costInEuros;
if (asset.token.addr == address(0)) {
nativePurchased += _portion;
} else {
IERC20(asset.token.addr).safeTransferFrom(manager, address(this), _portion);
}
}
}
}
positions[holders[j]] = _position;
}
if (burnEuros > 0) IEUROs(EUROs).burn(address(this), burnEuros);
returnUnpurchasedNative(_assets, nativePurchased);
}
_portion on line 223 further carried out arithmetic operations that increase the rounding issue cause large precision error that leads to loss of rewards for position holder.
_portion = _portion * _position.EUROs / costInEuros;
Impact
Carrying out arthimetic operation in function distributeAssets based on division of values, then multiplying and dividing and further multiplying and dividing will have resultant causing large precision error or even loss of rewards for users.
Tools Used
Manual Code Review
Recommendations
The recommendation is made in area of first conducting multiplication of all values and carries out all other division arithmetic operation.
function distributeAssets(ILiquidationPoolManager.Asset[] memory _assets, uint256 _collateralRate, uint256 _hundredPC) external payable {
consolidatePendingStakes();
(,int256 priceEurUsd,,,) = Chainlink.AggregatorV3Interface(eurUsd).latestRoundData();
uint256 stakeTotal = getStakeTotal();
uint256 burnEuros;
uint256 nativePurchased;
for (uint256 j = 0; j < holders.length; j++) {
Position memory _position = positions[holders[j]];
uint256 _positionStake = stake(_position);
if (_positionStake > 0) {
for (uint256 i = 0; i < _assets.length; i++) {
ILiquidationPoolManager.Asset memory asset = _assets[i];
if (asset.amount > 0) {
(,int256 assetPriceUsd,,,) = Chainlink.AggregatorV3Interface(asset.token.clAddr).latestRoundData();
- uint256 _portion = asset.amount * _positionStake / stakeTotal;
- uint256 costInEuros = _portion * 10 ** (18 - asset.token.dec) * uint256(assetPriceUsd) / uint256(priceEurUsd) * _hundredPC / _collateralRate;
+ uint256 _portion = (asset.amount * _positionStake) * 10 ** (18 - asset.token.dec) * uint256(assetPriceUsd) ;
+ uint256 costPriceRatio = (uint256(priceEurUsd) * _hundredPC ) / (stakeTotal * _collateralRate);
+ uint256 costInEuros = _portion / costPriceRatio;
if (costInEuros > _position.EUROs) {
_portion = _portion * _position.EUROs / costInEuros;
costInEuros = _position.EUROs;
}
_position.EUROs -= costInEuros;
rewards[abi.encodePacked(_position.holder, asset.token.symbol)] += _portion;
burnEuros += costInEuros;
if (asset.token.addr == address(0)) {
nativePurchased += _portion;
} else {
IERC20(asset.token.addr).safeTransferFrom(manager, address(this), _portion);
}
}
}
}
positions[holders[j]] = _position;
}
if (burnEuros > 0) IEUROs(EUROs).burn(address(this), burnEuros);
returnUnpurchasedNative(_assets, nativePurchased);
}
