[USN-2909-2] Linux kernel (Utopic HWE) regression

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-2909-2
February 27, 2016

linux-lts-utopic regression
==========================================================================

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

- Ubuntu 14.04 LTS

Summary:

USN-2909-1 introduced a regression in the Ubuntu 14.10 Linux kernel
backported to Ubuntu 14.04 LTS.

Software Description:
- linux-lts-utopic: Linux hardware enablement kernel from Utopic for Trusty

Details:

USN-2909-1 fixed vulnerabilities in the Ubuntu 14.10 Linux kernel
backported to Ubuntu 14.04 LTS. An incorrect locking fix caused a
regression that broke graphics displays for Ubuntu 14.04 LTS guests
running the Ubuntu 14.10 backport kernel within VMWare virtual
machines. This update fixes the problem.

We apologize for the inconvenience.

Original advisory 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   3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-generic-lpae  3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-lowlatency  3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-powerpc-e500mc  3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-powerpc-smp  3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-powerpc64-emb  3.16.0-62.83~14.04.1
  linux-image-3.16.0-62-powerpc64-smp  3.16.0-62.83~14.04.1

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

References:
  http://www.ubuntu.com/usn/usn-2909-2
  http://www.ubuntu.com/usn/usn-2909-1
  https://launchpad.net/bugs/1548587

Package Information:
  https://launchpad.net/ubuntu/+source/linux-lts-utopic/3.16.0-62.83~14.04.1

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