Shell Protocol - Fulum's results

[01] Code and comment mismatch

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L119-L125

Notice line is wrong, you need to change it.

/**
  -- @notice Calculates the b variable in the curve eq which is basically a sq. root of the inverse of x instantaneous price
  ++ @notice Calculates the b variable in the curve eq which is basically a sq. root of x instantaneous price
   @param self config instance
*/
function b(Config storage self) public view returns (int128) {
    return p_min(self).sqrt();
}

[02] Code and comment mismatch

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L254-L256

The comment doesn't match the code.

-- // at all times x price should be less than y price
++ // at all times y price should be less than x price
    if (py_init <= px_init) revert InvalidPrice();
    if (py_final <= px_final) revert InvalidPrice();
	

[03] Code and comment mismatch

In some functions, the amount must be less than 0 because the sign is inverted just after it. These comment lines doesn't match the code.

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L335-L336

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L450-L451

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L487-L488

-- // amount cannot be less than 0
++ // amount cannot be more than 0
    require(result < 0);

[04] Code and comment mismatch

The comment doesn't match the code.

https://github.com/code-423n4/2023-08-shell/blob/c61cf0e01bada04c3d6055acb81f61955ed600aa/src/proteus/EvolvingProteus.sol#L455-L490

 -- * @dev We use FEE_UP because we want to increase the perceived amount of
 -- *  reserve tokens leaving the pool and to increase the observed amount of
 -- *  LP tokens being burned.
 ++ * @dev We use FEE_DOWN because we want to decrease the perceived amount of
 ++ *  reserve tokens leaving the pool and to decrease the observed amount of
 ++ *  LP tokens.
 */
function withdrawGivenInputAmount(
    uint256 xBalance,
    uint256 yBalance,
    uint256 totalSupply,
    uint256 burnedAmount,
    SpecifiedToken withdrawnToken
) external view returns (uint256 withdrawnAmount) {

    ...

    int256 result = _lpTokenSpecified(
        withdrawnToken,
        -int256(burnedAmount),
        FEE_DOWN,
        int256(totalSupply),
        int256(xBalance),
        int256(yBalance)
    );