Liquidity Management
Gamma
DeFiFoundry
50,000 USDC
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Submission Details
Severity: medium
Invalid

Users Will Overpay For Execution Fees If Order Is A Market Swap Order

sakshamseth5

Summary

Users orders requesting a market swap order from GMX will always overpay for the execution fee , this is because oraclePriceCount has been hardcoded to 5

Vulnerability Details

Consider the following ->

1.) Leverage of the perp vault is 1x and positionIsClosed is false (1x long position).

2.) A user comes to deposit , calls deposit() and since positionIsClosed is false _payExecutionFee() is triggered (L238) ->

if (positionIsClosed) {
MarketPrices memory prices;
_mint(counter, amount, false, prices);
_finalize(hex'');
} else {
_payExecutionFee(counter, true);

3.) Inside _payExecutionFee() ->

function _payExecutionFee(uint256 depositId, bool isDeposit) internal {
uint256 minExecutionFee = getExecutionGasLimit(isDeposit) * tx.gasprice;

4.) Inside getExecutionGasLimit() since _isLongOneLeverage is true (1x long position) ->

function getExecutionGasLimit(bool isDeposit) public view returns (uint256 minExecutionGasLimit) {
if (positionIsClosed == false) {
if (_isLongOneLeverage(beenLong)) {
minExecutionGasLimit = gmxProxy.getExecutionGasLimit(Order.OrderType.MarketSwap, callbackGasLimit);
}

5.) getExecutionGasLimit() is called from GmxProxy.sol , and there the uint256 oraclePriceCount = 5; is hardcoded , for our normal swap order (Market Swap Order) we wouldn't need 5 oracles and would need maximum of two oracles , therefore multiplying by 5 will produce a way higher base gas limit ->

uint256 oraclePriceCount = 5; // maximum number of oralce prices
baseGasLimit +=
dataStore.getUint(ESTIMATED_GAS_FEE_PER_ORACLE_PRICE) *
oraclePriceCount;

Impact

Users are overcharged for the execution fees specially for swaps , and since excess fees sent to GMX is not refunded to users in gamma this is a loss of funds for the users.

Tools Used

Manual analysis

Recommendations

Dont' hardcode oraclePriceCount to 5.

Updates

Lead Judging Commences

n0kto Lead Judge 7 months ago
Submission Judgement Published
Invalidated
Reason: Design choice

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