USN-2908-5: Linux kernel (Wily HWE) regression

27 February 2016

linux-lts-wily regression

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

  • Ubuntu 14.04 LTS

Summary

USN-2908-2 introduced a regression in the Ubuntu 15.10 Linux kernel backported to Ubuntu 14.04 LTS.

Software Description

  • linux-lts-wily - Linux hardware enablement kernel from Wily for Trusty

Details

USN-2908-2 fixed vulnerabilities in the Ubuntu 15.10 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 15.10 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 did not properly enforce rlimits for file descriptors sent over UNIX domain sockets. A local attacker could use this to cause a denial of service. (CVE-2013-4312)

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)

Andy Lutomirski discovered a race condition in the Linux kernel’s translation lookaside buffer (TLB) handling of flush events. A local attacker could use this to cause a denial of service or possibly leak sensitive information. (CVE-2016-2069)

Update instructions

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

Ubuntu 14.04 LTS
linux-image-4.2.0-30-generic - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-generic-lpae - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-lowlatency - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-powerpc-e500mc - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-powerpc-smp - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-powerpc64-emb - 4.2.0-30.36~14.04.1
linux-image-4.2.0-30-powerpc64-smp - 4.2.0-30.36~14.04.1

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