0xShoonya - The swap mechanism does not have a deadline parameter

[sherlock-admin4]

0xShoonya

medium

The swap mechanism does not have a deadline parameter

Summary

The swap mechanism does not have a deadline parameter

Vulnerability Detail

swapExactAmountOut() in TpdaLiquidationPair.sol is missing the deadline parameter

    function swapExactAmountOut(
        address _receiver,
        uint256 _amountOut,
        uint256 _amountInMax,
        bytes calldata _flashSwapData
    ) external returns (uint256) {

The deadline check ensure that the transaction can be executed on time and the expired transaction revert.

Impact

The transaction can be pending in mempool for a long time and the trading activity is very time sensitive. Without deadline check, the trade transaction can be executed in a long time after the user submit the transaction, at that time, the trade can be done in a sub-optimal price, which harms user's position.

The deadline check ensure that the transaction can be executed on time and the expired transaction revert.

Code Snippet

https://github.com/sherlock-audit/2024-05-pooltogether/blob/1aa1b8c028b659585e4c7a6b9b652fb075f86db3/pt-v5-tpda-liquidator/src/TpdaLiquidationPair.sol#L122-L167

Tool used

Manual Review

Recommendation

Add a deadline timestamp parameter to the swapExactAmountOut() method and revert the transaction if the expiry has passed.

[nevillehuang]

Invalid, deadline check implemented in router, where the function is expected to be called as seen here. Any other calls would be the user taking their own risk. Also known issue from previous audit here