Security update for xen

Open Source Vulnerabilities SUSE-SU-2018:0638-1

This update for xen fixes several issues. This new feature was included: - add script and sysv service to watch for vcpu online/offline events in a HVM domU These security issues were fixed: - CVE-2017-5753, CVE-2017-5715, CVE-2017-5754: Prevent information leaks via side effects of speculative execution, aka 'Spectre' and 'Meltdown' attacks (bsc#1074562, bsc#1068032) - CVE-2018-5683: The vga_draw_text function allowed local OS guest privileged users to cause a denial of service (out-of-bounds read and QEMU process crash) by leveraging improper memory address validation (bsc#1076116). - CVE-2017-18030: The cirrus_invalidate_region function allowed local OS guest privileged users to cause a denial of service (out-of-bounds array access and QEMU process crash) via vectors related to negative pitch (bsc#1076180). - CVE-2017-15595: x86 PV guest OS users were able to cause a DoS (unbounded recursion, stack consumption, and hypervisor crash) or possibly gain privileges via crafted page-table stacking (bsc#1061081) - CVE-2017-17566: Prevent PV guest OS users to cause a denial of service (host OS crash) or gain host OS privileges in shadow mode by mapping a certain auxiliary page (bsc#1070158). - CVE-2017-17563: Prevent guest OS users to cause a denial of service (host OS crash) or gain host OS privileges by leveraging an incorrect mask for reference-count overflow checking in shadow mode (bsc#1070159). - CVE-2017-17564: Prevent guest OS users to cause a denial of service (host OS crash) or gain host OS privileges by leveraging incorrect error handling for reference counting in shadow mode (bsc#1070160). - CVE-2017-17565: Prevent PV guest OS users to cause a denial of service (host OS crash) if shadow mode and log-dirty mode are in place, because of an incorrect assertion related to M2P (bsc#1070163). - Added missing intermediate preemption checks for guest requesting removal of memory. This allowed malicious guest administrator to cause denial of service due to the high cost of this operation (bsc#1080635). - Because of XEN not returning the proper error messages when transitioning grant tables from v2 to v1 a malicious guest was able to cause DoS or potentially allowed for privilege escalation as well as information leaks (bsc#1080662). These non-security issues were fixed: - bsc#1035442: Increased the value of LIBXL_DESTROY_TIMEOUT from 10 to 100 seconds. If many domUs shutdown in parallel the backends couldn't keep up - bsc#1031382: Prevent VMs from crashing when migrating between dom0 hosts in case read() returns zero on the receiver side.