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

# DatingDapp Security Audit Report

sven

[H-01] LikeRegistry::likeUser never credits userBalances, locking every like payment forever

Description

// src/LikeRegistry.sol:38
likes[msg.sender][liked] = true; // @> msg.value is never credited to userBalances
​
// src/LikeRegistry.sol:51-52
uint256 matchUserOne = userBalances[from]; // @> always 0
uint256 matchUserTwo = userBalances[to]; // @> always 0

Risk

Likelihood: High
Impact: High

Proof of Concept

Alice and Bob each pay 1 ETH and match. The multisig holds 0, the registry holds 2 ETH, and withdrawFees reverts.

function test_H01_fundsLockedForever() public {
vm.prank(alice); reg.likeUser{value: 1 ether}(bob);
vm.prank(bob); reg.likeUser{value: 1 ether}(alice); // match
address msig = vm.computeCreateAddress(address(reg), 1); // deployed multisig
assertEq(msig.balance, 0);
assertEq(address(reg).balance, 2 ether); // stuck
vm.prank(deployer);
vm.expectRevert("No fees to withdraw");
reg.withdrawFees();
}

Recommended Mitigation

Credit the payment when the like is recorded:

likes[msg.sender][liked] = true;
+ userBalances[msg.sender] += msg.value;
emit Liked(msg.sender, liked);

Note that this exposes H-02 (per-user balance pooled across unrelated likes), which should be fixed together.

Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge about 2 hours 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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