xen: various flaws (#1490884)
    Missing NUMA node parameter verification [XSA-231, CVE-2017-14316]
    Missing check for grant table [XSA-232, CVE-2017-14318]
    cxenstored: Race in domain cleanup [XSA-233, CVE-2017-14317]
    insufficient grant unmapping checks for x86 PV guests [XSA-234, CVE-2017-14319]