Last Man Standing
First Flight #45
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Submission Details
Severity: medium
Valid

Platform Fee Calculation May Revert on Underflow

viveksh0062

Root + Impact

Description

  • In claimThrone():

uint256 currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
​
// Defensive check:
if (currentPlatformFee > (sentAmount - previousKingPayout)) {
currentPlatformFee = sentAmount - previousKingPayout;
}
​

But previousKingPayout is always 0, so this condition is pointless and might cause:

  • Over-allocation to platform fees

  • Loss of user trust

  • Unstable logic if payout code is added later

And if in future the previousKingPayout becomes non-zero (say 110% of sentAmount due to logic bug), subtraction underflows and causes a revert.

Risk

Impact:

  • Transfer blocked

  • Pot broken

Proof of Concept

Right now previousKingPayout == 0, but simulate a future update:

// Assume bug adds 110% payout in future
uint256 previousKingPayout = (sentAmount * 110) / 100;
uint256 currentPlatformFee = (sentAmount * platformFeePercentage) / 100;
​
// now: sentAmount - previousKingPayout < 0 → underflow → revert
​

Recommended Mitigation

Enforce safe arithmetic using SafeMath or require sentAmount >= previousKingPayout

  • Or simply remove the redundant check now and reimplement properly when king payout logic is added

Updates

Appeal created

inallhonesty Lead Judge about 1 month ago
Submission Judgement Published
Validated
Assigned finding tags:

Missing Previous King Payout Functionality

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