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 v4.9.285 by commit 8a558261fa57a6deefb0925ab1829f698b194aea, it was introduced in version v4.7 by commit 5d9e2ab9fea4cdf0a2522f5cbed2e7fbb220d757. For more details please see the references link.