Submitted by 0xsomeone
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L844
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L857
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L883
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L898
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L927
https://github.com/code-423n4/2022-05-rubicon/blob/main/contracts/RubiconMarket.sol#L951
The referenced lines all perform unsafe multiplications using the unitary denominations of either 1 ether (1e18) or 10**9 (1e9), both of which can easily lead to overflows when used as a multiplier for large amounts of assets.
Purchasing and selling amounts will be improperly fulfilled as well as improperly tracked as sold out / bought out.
We advise the codebase to make use of the mul operation exposed by the DSMath library already incorporated into the codebase to guarantee all operations are performed safely and cannot overflow.
Issue is deducible by inspecting the relevant lines referenced in the issue and making note of the raw multiplication (*) operations performed.
bghughes (Rubicon) confirmed 
HickupHH3 (judge) commented:
