Ubuntu Security Notice 2979-1 - David Matlack discovered that the Kernel-based Virtual Machine (KVM) implementation in the Linux kernel did not properly restrict variable Memory Type Range Registers (MTRR) in KVM guests. A privileged user in a guest VM could use this to cause a denial of service (system crash) in the host, expose sensitive information from the host, or possibly gain administrative privileges in the host. Philip Pettersson discovered that the Linux kernel's ASN.1 DER decoder did not properly process certificate files with tags of indefinite length. A local unprivileged attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code with administrative privileges. Various other issues were also addressed.
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==========================================================================Ubuntu Security Notice USN-2979-1
May 16, 2016
linux vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 16.04 LTS
Summary:
Several security issues were fixed in the kernel.
Software Description:
- linux: Linux kernel
Details:
David Matlack discovered that the Kernel-based Virtual Machine (KVM)
implementation in the Linux kernel did not properly restrict variable
Memory Type Range Registers (MTRR) in KVM guests. A privileged user in a
guest VM could use this to cause a denial of service (system crash) in the
host, expose sensitive information from the host, or possibly gain
administrative privileges in the host. (CVE-2016-3713)
Philip Pettersson discovered that the Linux kernel's ASN.1 DER decoder did
not properly process certificate files with tags of indefinite length. A
local unprivileged attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code with administrative
privileges. (CVE-2016-0758)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 16.04 LTS:
linux-image-4.4.0-22-generic 4.4.0-22.40
linux-image-4.4.0-22-generic-lpae 4.4.0-22.40
linux-image-4.4.0-22-lowlatency 4.4.0-22.40
linux-image-4.4.0-22-powerpc-e500mc 4.4.0-22.40
linux-image-4.4.0-22-powerpc-smp 4.4.0-22.40
linux-image-4.4.0-22-powerpc64-emb 4.4.0-22.40
linux-image-4.4.0-22-powerpc64-smp 4.4.0-22.40
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:
http://www.ubuntu.com/usn/usn-2979-1
CVE-2016-0758, CVE-2016-3713
Package Information:
https://launchpad.net/ubuntu/+source/linux/4.4.0-22.40