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 v4.9.306 by commit ae6f8a67b98144827e78874c8dba41cccb02be5b. For more details please see the references link.