xen/netfront: react properly to failing gnttabendforeignaccessref()
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 c4497b057b14274e159434f0ed70439a21f3d2a9. For more details please see the references link.