USN-2909-1: Linux kernel (Utopic HWE) vulnerabilities

22 February 2016

linux-lts-utopic vulnerabilities

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

  • Ubuntu 14.04 LTS

Summary

Several security issues were fixed in the kernel.

Software Description

  • linux-lts-utopic - Linux hardware enablement kernel from Utopic

Details

halfdog discovered that OverlayFS, when mounting on top of a FUSE mount, incorrectly propagated file attributes, including setuid. A local unprivileged attacker could use this to gain privileges. (CVE-2016-1576)

halfdog discovered that OverlayFS in the Linux kernel incorrectly propagated security sensitive extended attributes, such as POSIX ACLs. A local unprivileged attacker could use this to gain privileges. (CVE-2016-1575)

It was discovered that the Linux kernel’s Filesystem in Userspace (FUSE) implementation did not handle initial zero length segments properly. A local attacker could use this to cause a denial of service (unkillable task). (CVE-2015-8785)

Update instructions

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

Ubuntu 14.04 LTS
linux-image-3.16.0-62-generic - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-generic-lpae - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-lowlatency - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-powerpc-e500mc - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-powerpc-smp - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-powerpc64-emb - 3.16.0-62.82~14.04.1
linux-image-3.16.0-62-powerpc64-smp - 3.16.0-62.82~14.04.1

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

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