Submission Details
Severity:
Unnecessary IF statement in `MathMasters::mulWadUp` function
Description: The MathMasters::mulWadUp function has an unnecessary if statement that essentially checks if x == y and then increments x by 1, without providing any context or reason as to why this is necessary. This leads to imprecise returned values.
Impact: High, as it results in imprecise returned values
POC:
function test_mulWadUpOnEqualInput() public pure {
uint256 x = 5e18;
uint256 y = 5e18;
uint256 result = MathMasters.mulWadUp(x, y);
uint256 expected = x * y == 0 ? 0 : (x * y - 1) / 1e18 + 1;
assert(result != expected);
}
Recomendation:
/// @dev Equivalent to `(x * y) / WAD` rounded up.
function mulWadUp(uint256 x, uint256 y) internal pure returns (uint256 z) {
/// @solidity memory-safe-assembly
assembly {
// Equivalent to `require(y == 0 || x <= type(uint256).max / y)`.
if mul(y, gt(x, or(div(not(0), y), x))) {
mstore(0x0, 0xbac65e5b) // `MathMasters__MulWadFailed()`.
revert(0x1c, 0x04)
}
- if iszero(sub(div(add(z, x), y), 1)) {
- x := add(x, 1)
- }
z := add(iszero(iszero(mod(mul(x, y), WAD))), div(mul(x, y), WAD))
}
}
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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