Tadle
Tadle
DeFiFoundry
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Submission Details
Severity: medium
Valid

Protocol doesn't support fee-on-transfer tokens

almantare

Summary

The logic of the _transfer function does not provide for interaction with fee-on-transfer tokens.

https://github.com/Cyfrin/2024-08-tadle/blob/main/src/core/TokenManager.sol#L233

function _transfer(
address _token,
address _from,
address _to,
uint256 _amount,
address _capitalPoolAddr
) internal {
uint256 fromBalanceBef = IERC20(_token).balanceOf(_from);
uint256 toBalanceBef = IERC20(_token).balanceOf(_to);
​
if (
_from == _capitalPoolAddr &&
IERC20(_token).allowance(_from, address(this)) == 0x0
) {
ICapitalPool(_capitalPoolAddr).approve(address(this));
}
​
_safe_transfer_from(_token, _from, _to, _amount);
​
uint256 fromBalanceAft = IERC20(_token).balanceOf(_from);
uint256 toBalanceAft = IERC20(_token).balanceOf(_to);
​
if (fromBalanceAft != fromBalanceBef - _amount) {
revert TransferFailed();
}
​
if (toBalanceAft != toBalanceBef + _amount) {
revert TransferFailed();
}
}

Vulnerability Details

Impact

Fee-on-transfer can be added to whitelist tokens by mistake which will lead to confusion of users.

Tools Used

Recommendations

Add information in docs which ERC20 variations(weird erc20) does not supported by protocol or adopt protocol's code for such scenarious like fee-on-transfer tokens.

Updates

Lead Judging Commences

0xnevi Lead Judge about 1 year ago
Submission Judgement Published
Validated
Assigned finding tags:

finding-TokenManager-FOT-Rebasing

Valid medium, there are disruptions to the ability to take market actions. The following functions will be disrupted without the possibiliy of reaching settlement, since the respective offers cannot be created/listed regardless of mode when transferring collateral token required to the CapitalPool contract or when refunding token from user to capital pool during relisting. So withdrawal is not an issue - `createOffer()` - reverts [here](https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L96-L102) - `listOffer()` - reverts [here](https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L355-L362) - `relistOffer()` - reverts [here](https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L515-L521) - `createTaker()` - reverts [here](https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/PreMarkets.sol#L831-L836) I believe medium severity is appropriate although the likelihood is high and impact is medium (only some level of disruption i.e. FOT tokens not supported and no funds at risk)

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