Tadle

Summary

The createOffer function responsible for creating new offers in the trading system, contains a logical flaw in its validation of the eachTradeTax parameter. This flaw potentially allows for the creation of offers with exorbitant trade taxes.

Vulnerability Details

The function includes the following check:

if (params.eachTradeTax > Constants.EACH_TRADE_TAX_DECIMAL_SCALER) {
revert InvalidEachTradeTaxRate();
}

https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L49C6-L52C1

This validation is intended to ensure that the trade tax does not exceed 100%. However, it actually allows for a trade tax of up to 100% inclusive, rather than strictly less than 100%.

The comment in the function states:

• @dev eachTradeTax must be less than 100%, decimal scaler is 10000

https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L42C9-L42C77

This indicates that the EACH_TRADE_TAX_DECIMAL_SCALER is set to 10000, representing 100%. The current check allows for a trade tax equal to this value, which translates to a 100% tax.

The comment clearly states that the trade tax "must be less than 100%", but the implemented check allows for it to be equal to 100%.

Impact

It could lead to scenarios where trades occur but traders receive no value, essentially functioning as a value sink rather than a fair exchange mechanism.

Tools Used

Manual review

Recommendations

Modify the trade tax validation to strictly enforce a "less than 100%" rule:

if (params.eachTradeTax >= Constants.EACH_TRADE_TAX_DECIMAL_SCALER) {
revert InvalidEachTradeTaxRate();
}