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

Ubuntu Security Notice USN-2909-1

22nd 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 version:

Ubuntu 14.04 LTS:

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-smp 3.16.0-62.82~14.04.1

linux-image-3.16.0-62-generic 3.16.0-62.82~14.04.1

linux-image-3.16.0-62-powerpc64-emb 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

CVE-2015-8785, CVE-2016-1575, CVE-2016-1576