CVE-2015-2756

This xen update is based on upstream 4.5.2 maintenance release, and fixes the following security issues:

The vgic_v2_to_sgi function in arch/arm/vgic-v2.c in Xen 4.5.x, when running on ARM hardware with general interrupt controller (GIC) version 2, allows local guest users to cause a denial of service (host crash) by writing an invalid value to the GICD.SGIR register (CVE-2015-0268).

The ARM GIC distributor virtualization in Xen 4.4.x and 4.5.x allows local guests to cause a denial of service by causing a large number messages to be logged (CVE-2015-1563).

The emulation routines for unspecified X86 devices in Xen 3.2.x through 4.5.x does not properly initialize data, which allow local HVM guest users to obtain sensitive information via vectors involving an unsupported access size (CVE-2015-2044).

The HYPERVISOR_xen_version hypercall in Xen 3.2.x through 4.5.x does not properly initialize data structures, which allows local guest users to obtain sensitive information via unspecified vectors (CVE-2015-2045).

Xen 3.3.x through 4.5.x and the Linux kernel through 3.19.1 do not properly restrict access to PCI command registers, which might allow local guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response (CVE-2015-2150).

The x86 emulator in Xen 3.2.x through 4.5.x does not properly ignore segment overrides for instructions with register operands, which allows local guest users to obtain sensitive information, cause a denial of service (memory corruption), or possibly execute arbitrary code via unspecified vectors (CVE-2015-2151).

Xen 4.5.x and earlier enables certain default backends when emulating a VGA device for an x86 HVM guest qemu even when the configuration disables them, which allows local guest users to obtain access to the VGA console by (1) setting the DISPLAY environment variable, when compiled with SDL support, or connecting to the VNC server on (2) ::1 or (3) 127.0.0.1, when not compiled with SDL support (CVE-2015-2152).

Xen 4.3.x, 4.4.x, and 4.5.x, when using toolstack disaggregation, allows remote domains with partial management control to cause a denial of service (host lock) via unspecified domctl operations (CVE-2015-2751).

The XEN_DOMCTL_memory_mapping hypercall in Xen 3.2.x through 4.5.x, when using a PCI passthrough device, is not preemptable, which allows local x86 HVM domain users to cause a denial of service (host CPU consumption) via a crafted request to the device model (qemu-dm) (CVE-2015-2752).

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response (CVE-2015-2756).

Heap-based buffer overflow in the PCNET controller in QEMU allows remote attackers to execute arbitrary code by sending a packet with TXSTATUS_STARTPACKET set and then a crafted packet with TXSTATUS_DEVICEOWNS set (CVE-2015-3209).

Stack-based buffer overflow in the xl command line utility in Xen 4.1.x through 4.5.x allows local guest administrators to gain privileges via a long configuration argument (CVE-2015-3259).

Xen 4.2.x through 4.5.x does not initialize certain fields, which allows certain remote service domains to obtain sensitive information from memory via a (1) XEN_DOMCTL_gettscinfo or (2) XEN_SYSCTL_getdomaininfolist request (CVE-2015-3340).

The Floppy Disk Controller (FDC) in QEMU, as used in Xen 4.5.x and earlier and KVM, allows local guest users to cause a denial of service (out-of-bounds write and guest crash) or possibly execute arbitrary code via the (1) FD_CMD_READ_ID, (2) FD_CMD_DRIVE_SPECIFICATION_COMMAND, or other…

Xen was updated 4.4.2_01 to address three security issues and functional bugs.

The following vulnerabilities were fixed:

• Long latency MMIO mapping operations are not preemptible (XSA-125, CVE-2015-2752, bnc#922705)
• Unmediated PCI command register access in qemu (XSA-126, CVE-2015-2756, bnc#922706)
• Certain domctl operations may be abused to lock up the host (XSA-127, CVE-2015-2751, bnc#922709)

The following non-security bugs were fixed:

• xen dmesg contains bogus output in early boot (bnc#923758)
• Xentop doesn't display disk statistics for VMs using qdisks (bnc#921842)

The following functionality was enabled:

• Enable spice support in qemu for x86_64
• Add Qxl vga support

The Virtualization service XEN was updated to fix various bugs and security issues.

The following security issues have been fixed:

* 

  CVE-2015-2756: XSA-126: Unmediated PCI command register access in
  qemu could have lead to denial of service attacks against the host,
  if PCI cards are - passed through to guests.

* 

  XSA-125: Long latency MMIO mapping operations were not preemptible.

* 

  CVE-2015-2151: XSA-123: Instructions with register operands ignored
  eventual segment overrides encoded for them. Due to an insufficiently
  conditional assignment such a bogus segment override could have,
  however, corrupted a pointer used subsequently to store the result of
  the instruction.

* 

  CVE-2015-2045: XSA-122: The code handling certain sub-operations of
  the HYPERVISOR_xen_version hypercall failed to fully initialize all
  fields of structures subsequently copied back to guest memory. Due to
  this hypervisor stack contents were copied into the destination of
  the operation, thus becoming visible to the guest.

* 

  CVE-2015-2044: XSA-121: Emulation routines in the hypervisor dealing
  with certain system devices checked whether the access size by the
  guest is a supported one. When the access size is unsupported these
  routines failed to set the data to be returned to the guest for read
  accesses, so that hypervisor stack contents were copied into the
  destination of the operation, thus becoming visible to the guest.

Security Issues:

* CVE-2015-2044
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2044>
* CVE-2015-2045
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2045>
* CVE-2015-2151
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2151>
* CVE-2015-2756
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2756>

The Virtualization service XEN was updated to fix various bugs and security issues.

The following security issues have been fixed:

* 

  CVE-2015-2756: XSA-126: Unmediated PCI command register access in
  qemu could have lead to denial of service attacks against the host,
  if PCI cards are passed through to guests.

* 

  XSA-125: Long latency MMIO mapping operations were not preemptible.

* 

  CVE-2015-2151: XSA-123: Instructions with register operands ignored
  eventual segment overrides encoded for them. Due to an insufficiently
  conditional assignment such a bogus segment override could have,
  however, corrupted a pointer used subsequently to store the result of
  the instruction.

* 

  CVE-2015-2045: XSA-122: The code handling certain sub-operations of
  the HYPERVISOR_xen_version hypercall failed to fully initialize all
  fields of structures subsequently copied back to guest memory. Due to
  this hypervisor stack contents were copied into the destination of
  the operation, thus becoming visible to the guest.

* 

  CVE-2015-2044: XSA-121: Emulation routines in the hypervisor dealing
  with certain system devices checked whether the access size by the
  guest is a supported one. When the access size is unsupported these
  routines failed to set the data to be returned to the guest for read
  accesses, so that hypervisor stack contents were copied into the
  destination of the operation, thus becoming visible to the guest.

Also fixed:

* Regular crashes of dom-0 on different servers due to races in MCE
  access were fixed. bsc#907755

Security Issues:

* CVE-2015-2044
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2044>
* CVE-2015-2045
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2045>
* CVE-2015-2151
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2151>
* CVE-2015-2756
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2756>

The Virtualization service XEN was updated to fix various bugs and security issues.

The following security issues have been fixed:

* 

  CVE-2015-2756: XSA-126: Unmediated PCI command register access in
  qemu could have lead to denial of service attacks against the host,
  if PCI cards are passed through to guests.

* 

  XSA-125: Long latency MMIO mapping operations were not preemptible.

* 

  CVE-2015-2151: XSA-123: Instructions with register operands ignored
  eventual segment overrides encoded for them. Due to an insufficiently
  conditional assignment such a bogus segment override could have,
  however, corrupted a pointer used subsequently to store the result of
  the instruction.

* 

  CVE-2015-2045: XSA-122: The code handling certain sub-operations of
  the HYPERVISOR_xen_version hypercall failed to fully initialize all
  fields of structures subsequently copied back to guest memory. Due to
  this hypervisor stack contents were copied into the destination of
  the operation, thus becoming visible to the guest.

* 

  CVE-2015-2044: XSA-121: Emulation routines in the hypervisor dealing
  with certain system devices checked whether the access size by the
  guest is a supported one. When the access size is unsupported these
  routines failed to set the data to be returned to the guest for read
  accesses, so that hypervisor stack contents were copied into the
  destination of the operation, thus becoming visible to the guest.

Also fixed:

* Fully virtualized guest install from network source failed with
  'cannot find guest domain' in XEN. (bsc#919341)

Security Issues:

* CVE-2015-2044
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2044>
* CVE-2015-2045
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2045>
* CVE-2015-2151
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2151>
* CVE-2015-2756
  <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2756>

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

Jason Geffner discovered that QEMU incorrectly handled the virtual floppy driver. This issue is known as VENOM. A malicious guest could use this issue to cause a denial of service, or possibly execute arbitrary code on the host as the user running the QEMU process. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. (CVE-2015-3456)

Daniel P. Berrange discovered that QEMU incorrectly handled VNC websockets. A remote attacker could use this issue to cause QEMU to consume memory, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 14.10 and Ubuntu 15.04. (CVE-2015-1779)

Jan Beulich discovered that QEMU, when used with Xen, didn't properly restrict access to PCI command registers. A malicious guest could use this issue to cause a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 14.10. (CVE-2015-2756)