DatingDapp
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Submission Details
Severity: high
Valid

Missing User Balance Update in likeUser Leads to Incorrect Reward Calculation

howiecht

Summary

LikeRegistry::userBalances mapping is not updated correctly in LikeRegistry::LikeUser()function. This omission prevents the accurate calculation and distribution of rewards in subsequent function calls, specifically within the matchRewards() internal function.

Vulnerability Details

The userBalances mapping is crucial for tracking the accumulated funds associated with each user, which is used to calculate rewards in the matchRewards() internal function. However, the likeUser() function, which is responsible for initiating the "like" action and potentially triggering a match, fails to update the userBalances variable. This means that when a match occurs, and the matchRewards() function attempts to distribute rewards, it will not have access to the necessary balance information. Consequently, no rewards will be correctly calculated, resulting in zero rewards sent to the MultiSig contract, as the contract will believe there is no balance to distribute.

Proof of Code:

function testLikeProfile() public {
vm.deal(user, 10 ether);
vm.prank(user); // Simulates user calling the function
soulboundNFT.mintProfile("Alice", 25, "ipfs://profileImage");
​
vm.prank(user2); // Simulates user calling the function
soulboundNFT.mintProfile("Bob", 18, "ipfs://profileImage");
​
assert(registry.likes(user, user2) == false);
​
vm.startPrank(user);
registry.likeUser{value: 1 ether}(user2);
bool liked = registry.likes(user, user2);
assertTrue(liked, "User should be liked");
vm.stopPrank();
assert(registry.likes(user, user2) == true);
assertEq(registry.userBalances(user2), 0); // user2 balance has not updated
}

Impact

Users who participate in matching activities will not receive the expected rewards, frustrating users and damaging the platform's incentive structure.

Tools Used

Recommendations

To resolve this vulnerability, the userBalances mapping needs to be updated in the likeUser() function:

function likeUser(address liked) external payable {
require(msg.value >= 1 ether, "Must send at least 1 ETH");
require(!likes[msg.sender][liked], "Already liked");
require(msg.sender != liked, "Cannot like yourself");
require(profileNFT.profileToToken(msg.sender) != 0, "Must have a profile NFT");
require(profileNFT.profileToToken(liked) != 0, "Liked user must have a profile NFT");
​
likes[msg.sender][liked] = true;
emit Liked(msg.sender, liked);
​
+ userBalances[liked] += msg.value;
​
// Check if mutual like
if (likes[liked][msg.sender]) {
matches[msg.sender].push(liked);
matches[liked].push(msg.sender);
emit Matched(msg.sender, liked);
matchRewards(liked, msg.sender);
}
}

This change ensures that the userBalances mapping is updated correctly when a user likes another user, reflecting the payment associated with the like action, and setting a correct starting balance.

Updates

Appeal created

n0kto Lead Judge 5 months ago
Submission Judgement Published
Validated
Assigned finding tags:

finding_likeUser_no_userBalances_updated

Likelihood: High, always. Impact: High, loss of funds

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