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Tadle
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Submission Details
Severity: medium
Valid

ERC20 Rebasing/FOT feature

MSaptarshi007

Summary

Some ERC20 tokens such as stETH have a special feature of rebasing , which results in their balance changing from time to time, and some ERC20 also have a feature for FEE On Transfer

Vulnerability Details

Since Tadleis expected to support all kinds of ERC20 tokens and if one such token has gone through a rebasing/FOT users might not get their exact amount out.

Users can withdraw their tokens amount out from the capitalPool by withdrawing their claimable Amountfrom their [Balance mapping](https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/TokenManager.sol#L141)

Since if the balance changed later,the returned value will inaccurate and the amount used before and after that specific operation might differ

function withdraw(
address _tokenAddress,
TokenBalanceType _tokenBalanceType
) external whenNotPaused {
uint256 claimAbleAmount = userTokenBalanceMap[_msgSender()][
_tokenAddress
​
if (_tokenAddress == wrappedNativeToken) {
/**
* @dev token is native token
* @dev transfer from capital pool to msg sender
* @dev withdraw native token to token manager contract
* @dev transfer native token to msg sender
*/
_transfer(
wrappedNativeToken,
capitalPoolAddr,
address(this),
claimAbleAmount,
capitalPoolAddr
);
​
IWrappedNativeToken(wrappedNativeToken).withdraw(claimAbleAmount);
payable(msg.sender).transfer(claimAbleAmount);
} else {
/**
* @dev token is ERC20 token
* @dev transfer from capital pool to msg sender
*/
_safe_transfer_from(
_tokenAddress,
capitalPoolAddr,
_msgSender(),
claimAbleAmount
);
}
​
emit Withdraw(
_msgSender(),
_tokenAddress,
_tokenBalanceType,
claimAbleAmount
);
}
​

https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/TokenManager.sol#L175

Note: This problem also applies for WETHin blast chain since WETH has a rebasing functionality in that chain

The problem will be in the following functions createOffer, listOffer, relistOfferwhile depositing the amount

https://github.com/Cyfrin/2024-08-tadle/blob/04fd8634701697184a3f3a5558b41c109866e5f8/src/core/TokenManager.sol#L90

function tillIn(
address _accountAddress,
address _tokenAddress,
uint256 _amount,
bool _isPointToken
)
external
payable
onlyRelatedContracts(tadleFactory, _msgSender())
onlyInTokenWhiteList(_isPointToken, _tokenAddress)
{
/// @notice return if amount is 0
if (_amount == 0) {
return;
}
​
address capitalPoolAddr = tadleFactory.relatedContracts(
RelatedContractLibraries.CAPITAL_POOL
);
if (capitalPoolAddr == address(0x0)) {
revert Errors.ContractIsNotDeployed();
}
​
if (_tokenAddress == wrappedNativeToken) {
/**
* @dev token is native token
* @notice check msg value
* @dev if msg value is less than _amount, revert
* @dev wrap native token and transfer to capital pool
*/
if (msg.value < _amount) {
revert Errors.NotEnoughMsgValue(msg.value, _amount);
}
IWrappedNativeToken(wrappedNativeToken).deposit{value: _amount}();
@> _safe_transfer(wrappedNativeToken, capitalPoolAddr, _amount);
}
......
...../
emit TillIn(_accountAddress, _tokenAddress, _amount, _isPointToken);
}

Impact

The ultimate effect will be when the Token balance in the contract will be zero, while the internal acconting still registers that there are still amount available for users to collect

Tools Used

Manual Review

Recommendations

Query the balance before and after the transfer like it is done in internal _transfer function

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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