The xenmem_add_to_physmap_one function in arch/arm/mm.c in Xen 4.5.x, 4.4.x, and earlier does not limit the number of printk console messages when reporting a failure to retrieve a reference on a foreign page, which allows remote domains to cause a denial of service by leveraging permissions to map the memory of a foreign guest.
Debian Linux Security Advisory 3414-1 - Multiple security issues have been found in the Xen virtualisation solution, which may result in denial of service or information disclosure.