Security update for xen (important)

This update for xen fixes several issues.

These security issues were fixed:

• CVE-2016-7092: The get_page_from_l3e function in arch/x86/mm.c in Xen
  allowed local 32-bit PV guest OS administrators to gain host OS
  privileges via vectors related to L3 recursive pagetables (bsc#995785).
• CVE-2016-7093: Xen allowed local HVM guest OS administrators to
  overwrite hypervisor memory and consequently gain host OS privileges by
  leveraging mishandling of instruction pointer truncation during
  emulation (bsc#995789).
• CVE-2016-7094: Buffer overflow in Xen allowed local x86 HVM guest OS
  administrators on guests running with shadow paging to cause a denial of
  service via a pagetable update (bsc#995792).
• CVE-2016-6836: Information leakage in vmxnet3_complete_packet
  (bsc#994761).
• CVE-2016-6888: Integer overflow in packet initialisation in VMXNET3
  device driver. Aprivileged user inside guest c… (bsc#994772).
• CVE-2016-6833: Use after free while writing (bsc#994775).
• CVE-2016-6835: Buffer overflow in vmxnet_tx_pkt_parse_headers() in
  vmxnet3 deviceemulation. (bsc#994625).
• CVE-2016-6834: An infinite loop during packet fragmentation (bsc#994421).
• CVE-2016-6258: The PV pagetable code in arch/x86/mm.c in Xen allowed
  local 32-bit PV guest OS administrators to gain host OS privileges by
  leveraging fast-paths for updating pagetable entries (bsc#988675).
• CVE-2016-6259: Xen did not implement Supervisor Mode Access Prevention
  (SMAP) whitelisting in 32-bit exception and event delivery, which
  allowed local 32-bit PV guest OS kernels to cause a denial of service
  (hypervisor and VM crash) by triggering a safety check (bsc#988676).

These non-security issues were fixed:

• bsc#991934: Hypervisor crash in csched_acct
• bsc#992224: During boot of Xen Hypervisor, failed to get contiguous
  memory for DMA
• bsc#955104: Virsh reports error "one or more references were leaked
  after disconnect from hypervisor" when "virsh save" failed due to "no
  response from client after 6 keepalive messages"
• bsc#959552: Migration of HVM guest leads into libvirt segmentation fault
• bsc#993665: Migration of xen guests finishes in: One or more references
  were leaked after disconnect from the hypervisor
• bsc#959330: Guest migrations using virsh results in error "Internal
  error: received hangup / error event on socket"
• bsc#990500: VM virsh migration fails with keepalive error:
  ":virKeepAliveTimerInternal:143 : No response from client"
• bsc#953518: Unplug also SCSI disks in qemu-xen-traditional for upstream
  unplug protocol
• bsc#953518: xen_platform: unplug also SCSI disks in qemu-xen
• bsc#971949: xl: Support (by ignoring) xl migrate --live. xl migrations
  are always live
• bsc#970135: New virtualization project clock test randomly fails on Xen
• bsc#990970: Add PMU support for Intel E7-8867 v4 (fam=6, model=79)