xen-blkfront: Handle NULL gendisk
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 v5.18.8 by commit db403bc872af09360f5c80f83dc3b360f0be49af, it was introduced in version v5.14 by commit 05d69d950d9d84218fc9beafd02dea1f6a70e09e. For more details please see the references link.