V2ToV3Rollover Static Analysis Findings

VTV-01S: Improper Invocation of EIP-20 transfer

Type	Severity	Location
Standard Conformity		V2ToV3Rollover.sol:L184

Description:

The linked statement does not properly validate the returned bool of the EIP-20 standard transfer function. As the standard dictates, callers must not assume that false is never returned.

Impact:

If the code mandates that the returned bool is true, this will cause incompatibility with tokens such as USDT / Tether as no such bool is returned to be evaluated causing the check to fail at all times. On the other hand, if the token utilized can return a false value under certain conditions but the code does not validate it, the contract itself can be compromised as having received / sent funds that it never did.

Example:

Copy
184asset.transfer(address(VAULT), flashAmountDue);

Recommendation:

Since not all standardized tokens are EIP-20 compliant (such as Tether / USDT), we advise a safe wrapper library to be utilized instead such as SafeERC20 by OpenZeppelin to opportunistically validate the returned bool only if it exists.

Alleviation:

The SafeERC20::safeTransfer function is now properly utilized in place of the ERC20::transfer function invocation, ensuring that the asset is safely transferred to the VAULT and thus alleviating this exhibit.