Beedle - Oracle free perpetual lending

Summary

The transaction will always revert due to lack of approval

Vulnerability Details

function sellProfits(address _profits) public {
    require(_profits != WETH, "not allowed");
    uint256 amount = IERC20(_profits).balanceOf(address(this));


    ISwapRouter.ExactInputSingleParams memory params = ISwapRouter
        .ExactInputSingleParams({
            tokenIn: _profits,
            tokenOut: WETH,
            fee: 3000,
            recipient: address(this),
            deadline: block.timestamp,
            amountIn: amount,
            amountOutMinimum: 0,
            sqrtPriceLimitX96: 0
        });


    amount = swapRouter.exactInputSingle(params);
    IERC20(WETH).transfer(staking, IERC20(WETH).balanceOf(address(this)));
}

as we see it never called Approve the router to spend token

Impact

this makes the contract unable to swap tokens

Tools Used

manual review

Recommendations

add

function sellProfits(address _profits) public {
    require(_profits != WETH, "not allowed");
    uint256 amount = IERC20(_profits).balanceOf(address(this));


    ISwapRouter.ExactInputSingleParams memory params = ISwapRouter
        .ExactInputSingleParams({
            tokenIn: _profits,
            tokenOut: WETH,
            fee: 3000,
            recipient: address(this),
            deadline: block.timestamp,
            amountIn: amount,
            amountOutMinimum: 0,
            sqrtPriceLimitX96: 0
        });

 +   TransferHelper.safeApprove(_profits, address(swapRouter), amount);


    amount = swapRouter.exactInputSingle(params);
    IERC20(WETH).transfer(staking, IERC20(WETH).balanceOf(address(this)));
}