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USN-2850-1: Linux kernel vulnerabilities

19 December 2015

Several security issues were fixed in the kernel.

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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 consistency 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 consistency 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.
(http://bugs.launchpad.net/bugs/1527374, CVE-2015-8709)

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Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

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Update instructions

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

Ubuntu 15.04

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

Related notices

  • USN-2853-1: linux-image-4.2.0-22-powerpc64-emb, linux-image-4.2.0-22-lowlatency, linux-image-4.2.0-22-generic-lpae, linux-image-4.2.0-22-generic, linux-image-4.2.0-22-powerpc-smp, linux-image-4.2.0-22-powerpc-e500mc, linux-image-4.2.0-22-powerpc64-smp, linux-lts-wily, linux-image-extra-4.2.0-22-generic
  • USN-2846-1: linux-image-3.2.0-97-generic-pae, linux-image-3.2.0-97-powerpc-smp, linux-image-3.2.0-97-powerpc64-smp, linux, linux-image-3.2.0-97-omap, linux-image-3.2.0-97-generic, linux-image-3.2.0-97-highbank, linux-image-3.2.0-97-virtual
  • USN-2851-1: linux-image-4.2.0-22-powerpc64-emb, linux, linux-image-4.2.0-22-lowlatency, linux-image-4.2.0-22-generic-lpae, linux-image-4.2.0-22-generic, linux-image-4.2.0-22-powerpc-smp, linux-image-4.2.0-22-powerpc-e500mc, linux-image-4.2.0-22-powerpc64-smp
  • USN-2848-1: linux-image-3.13.0-74-powerpc-smp, linux-image-3.13.0-74-lowlatency, linux-image-3.13.0-74-generic-lpae, linux, linux-image-extra-3.13.0-74-generic, linux-image-3.13.0-74-powerpc-e500mc, linux-image-3.13.0-74-generic, linux-image-3.13.0-74-powerpc64-emb, linux-image-3.13.0-74-powerpc64-smp, linux-image-3.13.0-74-powerpc-e500
  • USN-2891-1: qemu-system-misc, qemu-system-sparc, qemu-system-common, qemu-common, qemu, qemu-guest-agent, qemu-keymaps, qemu-system-mips, qemu-system, qemu-user-static, qemu-system-aarch64, qemu-system-arm, qemu-user, qemu-utils, qemu-system-x86, qemu-kvm, qemu-system-ppc
  • USN-2886-2: linux-ti-omap4, linux-image-3.2.0-1476-omap4
  • USN-2849-1: linux-image-3.16.0-57-powerpc64-emb, linux-image-3.16.0-57-generic, linux-lts-utopic, linux-image-3.16.0-57-powerpc-e500mc, linux-image-extra-3.16.0-57-generic, linux-image-3.16.0-57-generic-lpae, linux-image-3.16.0-57-powerpc64-smp, linux-image-3.16.0-57-powerpc-smp, linux-image-3.16.0-57-lowlatency
  • USN-2854-1: linux-image-3.19.0-42-generic-lpae, linux-image-3.19.0-42-powerpc-e500mc, linux-image-3.19.0-42-powerpc64-smp, linux-lts-vivid, linux-image-3.19.0-42-lowlatency, linux-image-3.19.0-42-generic, linux-image-3.19.0-42-powerpc64-emb, linux-image-extra-3.19.0-42-generic, linux-image-3.19.0-42-powerpc-smp
  • USN-2847-1: linux-image-3.13.0-74-generic, linux-lts-trusty, linux-image-3.13.0-74-generic-lpae
  • USN-2852-1: linux-raspi2, linux-image-4.2.0-1017-raspi2

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