Security update for xen

Open Source Vulnerabilities SUSE-SU-2017:1146-1

This update for xen fixes several security issues: - A malicious 64-bit PV guest may be able to access all of system memory, allowing for all of privilege escalation, host crashes, and information leaks by placing a IRET hypercall in the middle of a multicall batch (XSA-213, bsc#1034843) - A malicious pair of guests may be able to access all of system memory, allowing for all of privilege escalation, host crashes, and information leaks because of a missing check when transfering pages via GNTTABOP_transfer (XSA-214, bsc#1034844). - CVE-2017-7718: hw/display/cirrus_vga_rop.h allowed local guest OS privileged users to cause a denial of service (out-of-bounds read and QEMU process crash) via vectors related to copying VGA data via the cirrus_bitblt_rop_fwd_transp_ and cirrus_bitblt_rop_fwd_ functions (bsc#1034994). - CVE-2016-9603: A privileged user within the guest VM could have caused a heap overflow in the device model process, potentially escalating their privileges to that of the device model process (bsc#1028655)