Allowance is not set to zero first before approving

Summary

approveTokens did not Approve to zero first. Some ERC20 tokens like USDT require resetting the approval to 0 first before being able to reset it to another value.

Vulnerability Detail

Some non-standard ERC20 tokens, such as USDT, require approve 0 first, otherwise they will revert. The approveTokens method in SdtUtilities is not handling this case which makes the modules incompatible with these tokens.

File: SdtUtilities.sol
214:     function approveTokens(TokenSpender[] calldata _tokenSpenders) external onlyOwner {
215:         for (uint256 i; i < _tokenSpenders.length; ) {
216:             IERC20(_tokenSpenders[i].token).approve(_tokenSpenders[i].spender, _tokenSpenders[i].amount);
217:             unchecked {
218:                 ++i;
219:             }
220:         }
221:     }

On Readme, it states, it will support USDT, thus this issue should be a valid medium one.

Impact

SdtUtilities is not compatible with certain ERC20 tokens for example USDT

Code Snippet

https://github.com/sherlock-audit/2023-11-convergence/blob/main/sherlock-cvg/contracts/utils/SdtUtilities.sol#L214-L221

Tool used

Manual Review

Recommendation

It is recommended to set the allowance to zero before increasing the allowance and use safeApprove/safeIncreaseAllowance.

Duplicate of #35

sherlock-audit / 2023-11-convergence-judging

chainNue - Allowance is not set to zero first before approving #203