xen/gnttab: fix gnttabendforeign_access() without page specified
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 v4.19.234 by commit 92dc0e4a219602242407dedd987dc9c8263c959b. For more details please see the references link.