Submission Details
Severity:
Use of Unlicensed Identifier
Summary
The contract includes the following line at the top:
// SPDX-License-Identifier: UNLICENSED
This identifier indicates that the contract is not licensed, but it also poses a potential issue from both a legal and technical perspective. The SPDX (Software Package Data Exchange) identifier is used to communicate the licensing terms under which the code is made available. In this case, the UNLICENSED label means the contract is not using a recognized open-source license, leaving the code without explicit permissions for others to use, distribute, or modify.
Vulnerability Details
The following test case demonstrates how the contract could fail due to excessive gas consumption from the loops in playersHand, dealersHand, and initializeDeck functions:
<details>
<summary>Code</summary>
```javascript
// In the `TwentyOne.t.sol` test file:
function testGasLimitOnExcessiveCards() public {
twentyOne = new TwentyOne();
address player = address(0x123);
vm.deal(player, 1 ether); // Fund the player with 1 ether
twentyOne.startGame{value: 1 ether}();
// Add a large number of cards to the player's hand (for testing purposes)
uint256 initialCards = 50; // Start with 50 cards
for (uint256 i = 0; i < initialCards; i++) {
twentyOne.hit(); // Keep adding cards to the player's hand
}
// Attempt to calculate the player's hand with too many cards
vm.expectRevert("Gas limit exceeded"); // Expect the function to fail due to excessive gas consumption
uint256 playerTotal = twentyOne.playersHand(player);
assert(playerTotal > 0); // The calculation should fail due to excessive gas usage
}
Impact
The contract is marked as UNLICENSED, which means users cannot assume it is free to use or modify. Without a specific open-source license, there is no assurance that third parties can legally use the code.
Recommended Mitigation:
Specify a License: To clarify the contract’s usage rights, it is advisable to specify a clear open-source license (e.g., MIT, GPL) if the intention is to allow others to use or contribute to the code. Example:
_<details>
<summary>Code</summary>
```diff
- // SPDX-License-Identifier: UNLICENSED
+ // SPDX-License-Identifier: MIT
```
</details>
Consult Legal Counsel: If the contract is intended to be proprietary, a more specific licensing approach or proprietary terms should be defined.
Tools Used
MANUAL REVIEW
Recommendations
Use License Identifier
Rewards breakdown
nSLOC
147This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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