Potential Underflow in withdrawInterest

Summary

In the withdrawInterest function, if totalInterest is less than amount, subtracting amount from totalInterest will cause an underflow and revert the transaction due to Solidity 0.8.x's checked arithmetic, even if totalInterestFromLiquidation has sufficient balance to cover the withdrawal.

Root Cause

The function checks the combined balance but only subtracts from totalInterest:

https://github.com/sherlock-audit/2024-11-autonomint/blob/0d324e04d4c0ca306e1ae4d4c65f0cb9d681751b/Blockchain/Blockchian/contracts/Core_logic/Treasury.sol#L616C1-L625C6

require(amount <= (totalInterest + totalInterestFromLiquidation), "Treasury don't have enough interest");
totalInterest -= amount;

If totalInterest < amount, this subtraction underflows and reverts.

Internal pre-conditions

none

External pre-conditions

none

Impact

DOS, underflow and revert.

PoC

1. Set totalInterest to 50 and totalInterestFromLiquidation to 100.
2. Attempt to withdraw an amount of 75.
3. The require passes because 75 ≤ 150.
4. Subtracting 75 from totalInterest (50) causes an underflow and reverts.

Mitigation

Implement logic to deduct the amount from totalInterest and totalInterestFromLiquidation proportionally or sequentially:

if (amount <= totalInterest) {
    totalInterest -= amount;
} else {
    uint256 remaining = amount - totalInterest;
    totalInterest = 0;
    totalInterestFromLiquidation -= remaining;
}