Possible incorrect gas price calculation on EIP-1559 chains
Title
Possible incorrect gas price calculation on EIP-1559 chains
Summary
Arbitrum and Avalanche use EIP-1559 gas pricing where tx.gasprice is not reliable.
The positionExecutionFee calculation in the gmxProxy contract's settle function uses tx.gasprice directly, which can cause problems.
Details
The actual gas price on these chains is calculated as: block.basefee + tx.priorityFeePerGas
Using tx.gasprice instead leads to paying more gas fees than needed, or failed transactions when gas fees are too low.
Impact
Users can pay more gas fees than needed, or fail transactions when gas fees are too low.
Tools Used
Manual Review
Recommendations
Calculate the real gas price by adding base fee and priority fee:
Lead Judging Commences
invalid_tx-gasprice_user_manipulation
If the sender does not provide enough, the transaction to create the order won't be included in the current block: no problem. If the user provides more, they will pay more: user mistake. Moreover, the `refundFee` is set to `true` only when the keeper is the caller, preventing manipulation.
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