nbd: fix possible overflow on 'firstminor' in nbddev_add()
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 v5.18 by commit 6d35d04a9e18990040e87d2bbf72689252669d54, it was introduced in version v4.11 by commit b0d9111a2d53785847763c64c40af2d4c4c5a8b7. For more details please see the references link.