USN-2909-2: Linux kernel (Utopic HWE) regression

Ubuntu Security Notice USN-2909-2

27th February, 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 version:

Ubuntu 14.04 LTS:: 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-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; linux-image-3.16.0-62-generic

3.16.0-62.83~14.04.1; linux-image-3.16.0-62-powerpc-smp

3.16.0-62.83~14.04.1

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.

References

LP: 1548587

Source: USN-2909-2: Linux kernel (Utopic HWE) regression

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