Liquidity Management

Description

When a user calls deposit() or withdraw(), these functions internally call: _payExecutionFee --> PerpetualVault::getExecutionGasLimit() --> GmxProxy::getExecutionGasLimit(). The function getExecutionGasLimit() in GmxProxy.sol fetches gasPerSwap correctly as:

but then assumes the swapPath length to be 1 & never bothers to multiply it with the correct swap hops.

Let's have a look at the GMX implementation. We can see here that SINGLE_SWAP_GAS_LIMIT key is retuned by the singleSwapGasLimitKey() function.

We can also see that a function like estimateExecuteDecreaseOrderGasLimit() (among many others) calculates the gas limit in the following manner:

Notice the gasPerSwap * swapCount term in the return statement. The Gamma implementation misses this or assumes that tokens like WBTC or LINK on both Arbitrum and Avalanche chains will be swappable with WETH in one hop, which is not necessarily true and GMX may use an optimized swap path with more than one hops.

Impact

User may end up paying less than required execution fee and the Keepers end up paying additional amount from their own pockets.

As the contest page specifies for Depositors:

Must provide sufficient execution fees for operations

Recommendation

Either fetch the swapPath hops from GMX and multiply that to gasPerSwap OR increase the buffer on top of the calculated gas limit to stay in the safe zone.