The Standard
The Standard
DeFiHardhat
20,000 USDC
View results
Previous Next
Submission Details
Severity: medium
Invalid

SmartVaultV3 : calculateMinimumAmountOut - incorrect calculation

ak1

Summary

The function calculateMinimumAmountOut has error in calculating the minimum amount value.

Vulnerability Details

calculateMinimumAmountOut would be used to calculate the minimum amount which will be used in swap.

https://github.com/Cyfrin/2023-12-the-standard/blob/91132936cb09ef9bf82f38ab1106346e2ad60f91/contracts/SmartVaultV3.sol#L206-L212

function calculateMinimumAmountOut(bytes32 _inTokenSymbol, bytes32 _outTokenSymbol, uint256 _amount) private view returns (uint256) {
ISmartVaultManagerV3 _manager = ISmartVaultManagerV3(manager);
uint256 requiredCollateralValue = minted * _manager.collateralRate() / _manager.HUNDRED_PC(); --------->> refer here.
uint256 collateralValueMinusSwapValue = euroCollateral() - calculator.tokenToEur(getToken(_inTokenSymbol), _amount);
return collateralValueMinusSwapValue >= requiredCollateralValue ?
0 : calculator.eurToToken(getToken(_outTokenSymbol), requiredCollateralValue - collateralValueMinusSwapValue);
}

In this line uint256 requiredCollateralValue = minted * _manager.collateralRate() / _manager.HUNDRED_PC(); the function tries to convert the minted EROs to asset value.
In the next line it uses the actual ERO value.

Overall this function uses both EURO and asset value when deciding the minimum amount value.

Impact

Incorrect minimum amount calculation.

Tools Used

Manual review.

Recommendations

https://github.com/Cyfrin/2023-12-the-standard/blob/91132936cb09ef9bf82f38ab1106346e2ad60f91/contracts/SmartVaultV3.sol#L206-L212

function calculateMinimumAmountOut(bytes32 _inTokenSymbol, bytes32 _outTokenSymbol, uint256 _amount) private view returns (uint256) {
ISmartVaultManagerV3 _manager = ISmartVaultManagerV3(manager);
uint256 requiredCollateralValue = minted * _manager.collateralRate() / _manager.HUNDRED_PC(); --------->> remove
uint256 requiredCollateralValue = minted; ----------------------------------------------------------->> add
uint256 collateralValueMinusSwapValue = euroCollateral() - calculator.tokenToEur(getToken(_inTokenSymbol), _amount);
return collateralValueMinusSwapValue >= requiredCollateralValue ?
0 : calculator.eurToToken(getToken(_outTokenSymbol), requiredCollateralValue - collateralValueMinusSwapValue);
}
Updates

Lead Judging Commences

hrishibhat Lead Judge over 1 year ago
Submission Judgement Published
Validated
Assigned finding tags:

Slippage-issue

hrishibhat Lead Judge over 1 year ago
Submission Judgement Published
Invalidated
Reason: Known issue
Assigned finding tags:

Slippage-issue

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.