Submission Details
Severity:
returned param `output` not used, so caller gets always zero return value.
Summary
The returned parameter output is not set to a valid value, and is always 0.
Vulnerability Details
The swapExactInput function has an output return parameter, but it is not set inside the function.
function swapExactInput(
IERC20 inputToken,
uint256 inputAmount,
IERC20 outputToken,
uint256 minOutputAmount,
uint64 deadline
)
public
revertIfZero(inputAmount)
revertIfDeadlinePassed(deadline)
returns (uint256 output)
{
uint256 inputReserves = inputToken.balanceOf(address(this));
uint256 outputReserves = outputToken.balanceOf(address(this));
uint256 outputAmount = getOutputAmountBasedOnInput(
inputAmount,
inputReserves,
outputReserves
);
if (outputAmount < minOutputAmount) {
revert TSwapPool__OutputTooLow(outputAmount, minOutputAmount);
}
_swap(inputToken, inputAmount, outputToken, outputAmount);
}
So while calling swapExactInput, users gets always zero value, so user should perform additional operation to get output amount by swap.
Impact
Result in bad user experience.
Tools Used
Manual review
Recommendations
function swapExactInput(
IERC20 inputToken,
uint256 inputAmount,
IERC20 outputToken,
uint256 minOutputAmount,
uint64 deadline
)
public
revertIfZero(inputAmount)
revertIfDeadlinePassed(deadline)
-- returns (uint256 output)
++ returns (uint256 outputAmount)
{
uint256 inputReserves = inputToken.balanceOf(address(this));
uint256 outputReserves = outputToken.balanceOf(address(this));
-- uint256 outputAmount = getOutputAmountBasedOnInput(
++ outputAmount = getOutputAmountBasedOnInput(
inputAmount,
inputReserves,
outputReserves
);
if (outputAmount < minOutputAmount) {
revert TSwapPool__OutputTooLow(outputAmount, minOutputAmount);
}
_swap(inputToken, inputAmount, outputToken, outputAmount);
}
Updates
Appeal created
inallhonesty over 1 year ago
Submission Judgement Published Assigned finding tags:
Default value returned by TSwapPool::swapExactInput results in incorrect return value given
Rewards breakdown
nSLOC
276This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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