First Flight #9: Soulmate
First Flight #9
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Submission Details
Severity: medium
Valid

In 'Soulmate.sol::mintSoulmateToken' an address can be it's own soulmate

coffee

Summary

In the 'Soulmate.sol::mintSoulmateToken' function, you can call the function a second time and possibly set yourself as your own soulmate.

Vulnerability Details

If you are the one waiting for a soulmate and then call the function again, you can set yourself as your own soulmate. This is because there is no check to see if the incoming soultmate2 is the same address that is already set as soulmate1.

Impact

This test passes showing that an address can be set as it's own soulmate.

function test_MintTokenToSelf() public {
uint256 tokenIdMinted = 0;
​
vm.prank(soulmate1);
soulmateContract.mintSoulmateToken();
​
assertTrue(soulmateContract.totalSupply() == 0);
​
vm.prank(soulmate1);
soulmateContract.mintSoulmateToken();
​
assertTrue(soulmateContract.totalSupply() == 1);
assertTrue(soulmateContract.soulmateOf(soulmate1) == soulmate1);
assertTrue(soulmateContract.ownerToId(soulmate1) == tokenIdMinted);
}

Tools Used

--Foundry

Recommendations

It is recommended to add a check to make sure that soulmate1 is not the same as the incoming msg.sender.

function mintSoulmateToken() public returns (uint256) {
// Check if people already have a soulmate, which means already have a token
address soulmate = soulmateOf[msg.sender];
if (soulmate != address(0))
revert Soulmate__alreadyHaveASoulmate(soulmate);
​
address soulmate1 = idToOwners[nextID][0];
address soulmate2 = idToOwners[nextID][1];
+ if (soulmate1 == msg.sender) {
+ revert Soulmate__cannotBeYourOwnSoulmate(soulmate);
+ }
if (soulmate1 == address(0)) {
idToOwners[nextID][0] = msg.sender;
ownerToId[msg.sender] = nextID;
emit SoulmateIsWaiting(msg.sender);
} else if (soulmate2 == address(0)) {
idToOwners[nextID][1] = msg.sender;
// Once 2 soulmates are reunited, the token is minted
ownerToId[msg.sender] = nextID;
soulmateOf[msg.sender] = soulmate1;
soulmateOf[soulmate1] = msg.sender;
idToCreationTimestamp[nextID] = block.timestamp;
​
emit SoulmateAreReunited(soulmate1, soulmate2, nextID);
​
_mint(msg.sender, nextID++);
}
​
return ownerToId[msg.sender];
}
Updates

Lead Judging Commences

0xnevi Lead Judge over 1 year ago
Submission Judgement Published
Validated
Assigned finding tags:

finding-self-soulmate

- Given the native anonymous nature of blockchain in general, this issue cannot be avoided unless an explicit whitelist is implemented. Even then we can only confirm soulmates are distinct individuals via kyc. I believe finding a soulmate is intended to be permisionless. - However, even though sufficient (500_000_000e18 in each vault) tokens are minted to claim staking and airdrop rewards, it would take 500_000_000 / 2 combined weeks for airdrop vault to be drained which is not unreasonable given there are [80+ million existing wallets](https://coinweb.com/trends/how-many-crypto-wallets-are-there/). Given there is no option to mint new love tokens, this would actually ruin the functionality of the protocol of finding soulmates and shift the focus to abusing a sybil attack to farming airdrops instead. Assigning medium severity for now but am open for appeals otherwise, since most if not all issues lack indepth analysis of the issue.

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