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=========================================================================Ubuntu Security Notice USN-2851-1
December 19, 2015

linux vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 15.10

Summary:

Several security issues were fixed in the kernel.

Software Description:
- linux: Linux kernel

Details:

Felix Wilhelm discovered a race condition in the Xen paravirtualized
drivers which can cause double fetch vulnerabilities. An attacker in the
paravirtualized guest could exploit this flaw to cause a denial of service
(crash the host) or potentially execute arbitrary code on the host.
(CVE-2015-8550)

Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not
perform sanity checks on the device's state. An attacker could exploit this
flaw to cause a denial of service (NULL dereference) on the host.
(CVE-2015-8551)

Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not
perform sanity checks on the device's state. An attacker could exploit this
flaw to cause a denial of service by flooding the logging system with
WARN() messages causing the initial domain to exhaust disk space.
(CVE-2015-8552)

Jann Horn discovered a ptrace issue with user namespaces in the Linux
kernel. The namespace owner could potentially exploit this flaw by ptracing
a root owned process entering the user namespace to elevate its privileges
and potentially gain access outside of the namespace.
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1527374)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 15.10:
  linux-image-4.2.0-22-generic    4.2.0-22.27
  linux-image-4.2.0-22-generic-lpae  4.2.0-22.27
  linux-image-4.2.0-22-lowlatency  4.2.0-22.27
  linux-image-4.2.0-22-powerpc-e500mc  4.2.0-22.27
  linux-image-4.2.0-22-powerpc-smp  4.2.0-22.27
  linux-image-4.2.0-22-powerpc64-emb  4.2.0-22.27
  linux-image-4.2.0-22-powerpc64-smp  4.2.0-22.27

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  https://ubuntu.com/security/notices/USN-2851-1
  CVE-2015-8550, CVE-2015-8551, CVE-2015-8552, https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1527374

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.2.0-22.27


Ubuntu 2851-1: Linux kernel vulnerabilities

December 20, 2015
Several security issues were fixed in the kernel.

Summary

Update Instructions

The problem can be corrected by updating your system to the following package versions: Ubuntu 15.10: linux-image-4.2.0-22-generic 4.2.0-22.27 linux-image-4.2.0-22-generic-lpae 4.2.0-22.27 linux-image-4.2.0-22-lowlatency 4.2.0-22.27 linux-image-4.2.0-22-powerpc-e500mc 4.2.0-22.27 linux-image-4.2.0-22-powerpc-smp 4.2.0-22.27 linux-image-4.2.0-22-powerpc64-emb 4.2.0-22.27 linux-image-4.2.0-22-powerpc64-smp 4.2.0-22.27 After a standard system update you need to reboot your computer to make all the necessary changes. ATTENTION: Due to an unavoidable ABI change the kernel updates have been given a new version number, which requires you to recompile and reinstall all third party kernel modules you might have installed. Unless you manually uninstalled the standard kernel metapackages (e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual, linux-powerpc), a standard system upgrade will automatically perform this as well.

References

https://ubuntu.com/security/notices/USN-2851-1

CVE-2015-8550, CVE-2015-8551, CVE-2015-8552, https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1527374

Severity
December 19, 2015

Package Information

https://launchpad.net/ubuntu/+source/linux/4.2.0-22.27

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