[USN-2643-2] Linux kernel regression

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==========================================================================
Ubuntu Security Notice USN-2643-2
June 21, 2015

linux regression
==========================================================================

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

- Ubuntu 14.04 LTS

Summary:

The system could be made to crash under certain conditions.

Software Description:
- linux: Linux kernel

Details:

The Fix for CVE-2015-1328 introduced a regression into the Linux kernel's
overlayfs file system. The removal of a directory that only exists on the
lower layer results in a kernel panic.

We apologize for the inconvenience.

Original advisory details:

Philip Pettersson discovered a privilege escalation when using overlayfs
mounts inside of user namespaces. A local user could exploit this flaw to
gain administrative privileges on the system.

Update instructions:

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

Ubuntu 14.04 LTS:
linux-image-3.13.0-55-generic 3.13.0-55.94
linux-image-3.13.0-55-generic-lpae 3.13.0-55.94
linux-image-3.13.0-55-lowlatency 3.13.0-55.94
linux-image-3.13.0-55-powerpc-e500 3.13.0-55.94
linux-image-3.13.0-55-powerpc-e500mc 3.13.0-55.94
linux-image-3.13.0-55-powerpc-smp 3.13.0-55.94
linux-image-3.13.0-55-powerpc64-emb 3.13.0-55.94
linux-image-3.13.0-55-powerpc64-smp 3.13.0-55.94

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

References:
http://www.ubuntu.com/usn/usn-2643-2
http://www.ubuntu.com/usn/usn-2643-1
http://bugs.launchpad.net/bugs/1465998

Package Information:
https://launchpad.net/ubuntu/+source/linux/3.13.0-55.94