DatingDapp
First Flight #33
Beginner FriendlyFoundrySolidityNFT
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Submission Details
Severity: low
Invalid

Redundant Type Casting in SoulboundProfileNFT Metadata

prashikshit

Summary

The tokenURI function in the SoulboundProfileNFT contract includes a redundant explicit type cast of the age field (stored as uint8) to uint256 before converting it to a string. While functionally harmless, this redundancy adds unnecessary complexity and deviates from Solidity best practices for type handling.

Vulnerability Details

Location

  • Contract: SoulboundProfileNFT.sol

  • Function: tokenURI

Root Cause

  • The age field is stored as a uint8 in the Profile struct.

  • When converting age to a string, the code explicitly casts it to uint256 before calling Strings.toString():

    uint256 profileAge = _profiles[tokenId].age; // Redundant cast
    Strings.toString(profileAge);

  • Why This Is Redundant:

    • Solidity automatically converts smaller integer types (e.g., uint8) to uint256 during operations.

    • The Strings.toString() function accepts uint256 as input, making the explicit cast unnecessary.

Code Snippet

function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
// ... existing checks ...
uint256 profileAge = _profiles[tokenId].age; // Unnecessary cast from uint8 to uint256
// ... rest of the code ...
}

Impact

Severity: Informational

  • No Functional Impact: The code operates correctly, and the cast does not affect the output.

  • Code Quality: Redundant operations reduce readability and may confuse developers during audits or maintenance.

  • Gas Efficiency: The explicit cast consumes a trivial amount of unnecessary gas (minor).

Recommended Mitigation

Fix

Remove the redundant cast by directly passing _profiles[tokenId].age to Strings.toString():

function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
// ... existing checks ...
string memory profileName = _profiles[tokenId].name;
uint8 profileAge = _profiles[tokenId].age; // Use uint8 directly
string memory imageURI = _profiles[tokenId].profileImage;
return string(
abi.encodePacked(
'{"name":"', profileName, '", ',
'"description":"A soulbound dating profile NFT.", ',
'"attributes": [{"trait_type": "Age", "value": ',
Strings.toString(profileAge), // Implicitly cast to uint256
"}], ",
'"image":"', imageURI, '"}'
)
);
}
Updates

Appeal created

n0kto Lead Judge 8 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Informational or Gas

Please read the CodeHawks documentation to know which submissions are valid. If you disagree, provide a coded PoC and explain the real likelyhood and the detailed impact on the mainnet without any supposition (if, it could, etc) to prove your point.

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