DatingDapp
AI First Flight #6
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EXP
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Submission Details
Severity: high
Valid

LikeRegistry Never Increments UserBalances, So Any Funds Sent to the Contract Are Permanently Stuck

jamie54781

LikeRegistry Never Increments UserBalances, So Any Funds Sent to the Contract Are Permanently Stuck

Description

The LikeRegistry::userBalances mapping values are never incremented. This means that even if two users match, no funds are sent to the resultant multisig contract, and the totalFees amount does not increase. This completely breaks the functionality of the smart contract.

// In this function, userBalances[msg.sender] is never incremented.
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);
​
// 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);
}
}

Risk

Likelihood:

  • This will affect any use of the smart contract.

Impact:

  • This completely breaks the intended functionality, as any funds sent using the likeUser function are permanently locked.

Proof of Concept

The following test demonstrates that even if two users get a match, their funds are never released. This means that the totalFees value is also never incremented, which causes the call to withdrawFees to revert.

event Matched(address indexed user1, address indexed user2);
function testLikeRegistryNeverAddsFunds() public {
vm.prank(user);
soulboundNFT.mintProfile("Alice", 25, "ipfs://profileImage");
​
vm.prank(user2);
soulboundNFT.mintProfile("Bob", 30, "ipfs://profileImage2");
​
vm.deal(user, 1 ether);
vm.prank(user);
likeRegistry.likeUser{value: 1 ether}(user2);
​
assertEq(address(likeRegistry).balance, 1 ether);
// User still isn't assigned any balance
assertEq(likeRegistry.userBalances(user), 0 ether);
​
vm.deal(user2, 1 ether);
vm.prank(user2);
vm.expectEmit(address(likeRegistry));
emit LikeRegistry.Matched(user2, user);
likeRegistry.likeUser{value: 1 ether}(user);
​
vm.prank(owner);
vm.expectRevert("No fees to withdraw");
likeRegistry.withdrawFees();
}

Recommended Mitigation

Accounting for the amount sent in the likeUser function should fix this issue.

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;
+ userBalances[msg.sender] += msg.value;
emit Liked(msg.sender, liked);
​
// 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);
}
}
Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge 1 day ago
Submission Judgement Published
Validated
Assigned finding tags:

[H-01] After the user calls the `likeUser` function, the userBalance does not increase by the corresponding value.

## Description User A calls `likeUser` and sends `value > 1` ETH. According to the design of DatingDapp, the amount for user A should be accumulated by `userBalances`. Otherwise, in the subsequent calculations, the balance for each user will be 0. ## Vulnerability Details When User A calls `likeUser`, the accumulation of `userBalances` is not performed. ```solidity 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); // 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 will result in `totalRewards` always being 0, affecting all subsequent calculations: ```solidity uint256 totalRewards = matchUserOne + matchUserTwo; uint256 matchingFees = (totalRewards * FIXEDFEE ) / 100; uint256 rewards = totalRewards - matchingFees; totalFees += matchingFees; ``` ## POC ```solidity function testUserBalanceshouldIncreaseAfterLike() public { vm.prank(user1); likeRegistry.likeUser{value: 20 ether}(user2); assertEq(likeRegistry.userBalances(user1), 20 ether, "User1 balance should be 20 ether"); } ``` Then we will get an error: ```shell [FAIL: User1 balance should be 20 ether: 0 != 20000000000000000000] ``` ## Impact - Users will be unable to receive rewards. - The contract owner will also be unable to withdraw ETH from the contract. ## Recommendations Add processing for `userBalances` in the `likeUser` function: ```diff 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; + userBalances[msg.sender] += msg.value; emit Liked(msg.sender, liked); [...] } ```

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