XDEFI contest - bitbopper's results

Handle

bitbopper

Vulnerability details

Impact

https://github.com/XDeFi-tech/xdefi-distribution/blob/3856a42df295183b40c6eee89307308f196612fe/contracts/XDEFIDistribution.sol#L51:L56 could be more gas efficient

Proof of Concept

Version as in Repo

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.6;

contract LockProofOld {
	uint256 _locked = 0;

	modifier noReenter() {
		require(_locked == 0, "LOCKED");
		_locked = uint256(1);
		_;
		_locked = uint256(0);
	}

	function test() public noReenter {
	}

}

Proposed Version

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.6;

contract LockProofNew {
	uint256 _locked = 1;

	modifier noReenter() {
		require(_locked == 1, "LOCKED");
		_locked = uint256(2);
		_;
		_locked = uint256(1);
	}

	function test() public noReenter {
	}

}

Comparison

Test harness

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.6;

import "ds-test/test.sol";

import "./LockProofOld.sol";
import "./LockProofNew.sol";

contract LockProofTest is DSTest {
    LockProofOld lockproofold;
    LockProofNew lockproofnew;

    function setUp() public {
        lockproofold = new LockProofOld();
        lockproofnew = new LockProofNew();
    }

    function test_old() public {
		lockproofold.test();
    }

    function test_new() public {
		lockproofnew.test();
    }
}

Output

dapp test
Running 2 tests for src/LockProof.t.sol:LockProofTest
[PASS] test_old() (gas: 21042)
[PASS] test_new() (gas: 1136)

Tools Used

Recommended Mitigation Steps