Vanguard
First Flight #56
Beginner FriendlyDeFiFoundry
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Submission Details
Impact: medium
Likelihood: medium

Unused State Variables Waste Gas and Imply Non-Existent Functionality

Author Revealed upon completion

Description

  • Several state variables are declared and initialized but never updated or used:

    • totalPenaltyFeesCollected - Always remains 0

    • addressTotalSwaps - Mapping is never written to

    • addressPenaltyCount - Mapping is never written to

// These are declared but never used
uint256 public totalPenaltyFeesCollected; // @> Never updated, always 0
​
mapping(address => uint256) public addressTotalSwaps; // @> Never written
mapping(address => uint256) public addressPenaltyCount; // @> Never written

Risk

Likelihood:

  • These unused variables exist in every deployment

Impact:

  • Extra gas cost for storage slot initialization (cold storage access)

  • Misleading public interface - external parties may expect these to contain data

  • Code suggests penalty tracking exists when it doesn't

  • Potential confusion in audits and integrations

Proof of Concept

Execute 5 penalty-triggering swaps - all tracking variables remain 0.

function test_UnusedStateVariables() public {
// totalPenaltyFeesCollected is always 0
assertEq(antiBotHook.totalPenaltyFeesCollected(), 0, "Always 0");
// Do some swaps that trigger penalties
vm.deal(bot1, 10 ether);
vm.startPrank(bot1);
SwapParams memory params = SwapParams({
zeroForOne: true,
amountSpecified: -int256(0.001 ether),
sqrtPriceLimitX96: TickMath.MIN_SQRT_PRICE + 1
});
PoolSwapTest.TestSettings memory testSettings =
PoolSwapTest.TestSettings({takeClaims: false, settleUsingBurn: false});
// Multiple rapid swaps should trigger penalties
for (uint i = 0; i < 5; i++) {
swapRouter.swap{value: 0.001 ether}(key, params, testSettings, ZERO_BYTES);
}
vm.stopPrank();
// Still 0 - never updated
assertEq(antiBotHook.totalPenaltyFeesCollected(), 0, "Still 0 after penalties");
assertEq(antiBotHook.addressTotalSwaps(address(swapRouter)), 0, "Never tracked");
assertEq(antiBotHook.addressPenaltyCount(address(swapRouter)), 0, "Never tracked");
}

Recommended Mitigation

Remove unused variables or implement actual tracking.

Option 1: Remove unused variables

- uint256 public totalPenaltyFeesCollected;
- mapping(address => uint256) public addressTotalSwaps;
- mapping(address => uint256) public addressPenaltyCount;

Option 2: Implement the tracking (if intended)

function _beforeSwap(...) internal override returns (...) {
// ... existing logic ...
+ addressTotalSwaps[sender] += 1;
if (applyPenalty) {
feeOverride = uint24((phasePenaltyBps * 100));
+ addressPenaltyCount[sender] += 1;
+ // Note: tracking actual fee amount collected would require afterSwap hook
}
// ...
}

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