Submission Details
Severity:
mulWadUp performs unnecessary round up.
Summary
The mulWadUp performs unnecessary round up.
Vulnerability Details
The assembly operation in line 56 of MathMasters.sol results in true even when x is equal to y. Valid round up operations is included on line 57, iszero(iszero(mod(mul(x, y), WAD))).
The test below represents the case when mulWadUp rounds up the result even when x is equal to y.
function testMulWadUpWithUnnecessaryRoundUp() public {
uint256 x = 1e18;
uint256 y = 1e18;
uint256 z = MathMasters.mulWadUp(x, y);
assertNotEq(z, 1e18);
assertEq(z, 1e18 + 1);
}
Add the test in MathMasters.t.sol and run forge test -vvvv --mt testMulWadUpWithUnnecessaryRoundUp to see the result.
$ forge test -vvvv --mt testMulWadUpWithUnnecessaryRoundUp
[⠑] Compiling...
No files changed, compilation skipped
Running 1 test for test/MathMasters.t.sol:MathMastersTest
[PASS] testMulWadUpWithUnnecessaryRoundUp() (gas: 759)
Traces:
[759] MathMastersTest::testMulWadUpWithUnnecessaryRoundUp()
└─ ← ()
Test result: ok. 1 passed; 0 failed; 0 skipped; finished in 1.67ms
Ran 1 test suites: 1 tests passed, 0 failed, 0 skipped (1 total tests)
Impact
Unnecessary round up leads to losses in the context of calculating token amount.
Tools Used
Foundry
Recommendations
Delete line 56.
Updates
Lead Judging Commences
inallhonesty almost 2 years ago
Submission Judgement Published Assigned finding tags:
`mulWadUp` has an unnecessary line that makes the result wrong for some inputs
Rewards breakdown
nSLOC
46This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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