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 v4.14.271 by commit 1b9f4115738af90427a8c94a3980bc52fbb23296. For more details please see the references link.