QuantAMM

Summary

In the UpliftOnlyExample::onAfterSwap function, an incorrect calculation of the admin fee (adminFee) leads to scenarios where the entire fee is allocated to the admin, leaving no rewards for the owner. This issue arises due to the division-based calculation method that fails in certain cases because of Solidity's integer math.

Vulnerability Details

The issue lies in this calculation:

Since Solidity does not support floating-point arithmetic, the calculation can result in a rounding error, causing adminFee to be calculated more than expected or as equal to hookFee under specific values.

POC

Unit test:

Impact

The owner loses their rightful share of the rewards, resulting in an unfair distribution of fees.

Tools Used

• Manual Review

• Fuzz Testing

Recommendations

Replace the current calculation of adminFee with a multiplication-based approach to avoid precision loss.
By rewriting the formula, we eliminate the intermediate division, preventing rounding issues and ensuring a fair split between adminFee and ownerFee.

In math, we can change the calculation like this:
(a/b) / (c/d) = (a*d) / (b*c)
so:
(hookFee) / (1e18/quantAMMFeeTake) = (hookFee/1) / (1e18/quantAMMFeeTake) = (hookFee*quantAMMFeeTake) / (1e18)

Code Diff