mcb: fix error handling in mcballocbus()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v4.14.249 by commit 115b07d9f47e3996430b8f2007edd9768e1f807f, it was introduced in version v4.7 by commit 5d9e2ab9fea4cdf0a2522f5cbed2e7fbb220d757. For more details please see the references link.