The Standard
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Submission Details
Severity: medium
Invalid

`claimRewards` / `findRewards` functions are vulnerable to read only reentrancy

cosine

Summary

The claimRewards function inside the LiquidationPool contract can be used by stakers to claim their rewards. As native ether is transferred to the user during this function call, reentering is possible. This function and the findRewards function both do not implement a reentrancy guard. Therefore, an external contract could read from findRewards while the rewards are currently being withdrawn.

Vulnerability Details

Here we can see both functions and that claimRewards allows reentering when receiving native ether, while findRewards reads from the same mapping and both miss a reentrancy guard:

function claimRewards() external {
ITokenManager.Token[] memory _tokens = ITokenManager(tokenManager).getAcceptedTokens();
for (uint256 i = 0; i < _tokens.length; i++) {
ITokenManager.Token memory _token = _tokens[i];
uint256 _rewardAmount = rewards[abi.encodePacked(msg.sender, _token.symbol)];
if (_rewardAmount > 0) {
delete rewards[abi.encodePacked(msg.sender, _token.symbol)];
if (_token.addr == address(0)) {
(bool _sent,) = payable(msg.sender).call{value: _rewardAmount}("");
require(_sent);
} else {
IERC20(_token.addr).transfer(msg.sender, _rewardAmount);
}
}
​
}
}
​
function findRewards(address _holder) private view returns (Reward[] memory) {
ITokenManager.Token[] memory _tokens = ITokenManager(tokenManager).getAcceptedTokens();
Reward[] memory _rewards = new Reward[](_tokens.length);
for (uint256 i = 0; i < _tokens.length; i++) {
_rewards[i] = Reward(_tokens[i].symbol, rewards[abi.encodePacked(_holder, _tokens[i].symbol)], _tokens[i].dec);
}
return _rewards;
}

Therefore, a read only reentrancy possibility occurs.

Impact

The missing guards could lead to critical vulnerabilities in third party protocols that want to build on top of the standard.

Recommendations

Implement a reentrancy guard in the claimRewards function and a read only reentrancy guard in the findRewards function.

Updates

Lead Judging Commences

hrishibhat Lead Judge almost 2 years ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

claims-reentrancy

informational/invalid

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