USN-2908-4: Linux kernel regression

26 February 2016

linux regression

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

  • Ubuntu 15.10

Summary

USN-2908-1 introduced a regression in the Linux kernel.

Software Description

  • linux - Linux kernel

Details

USN-2908-1 fixed vulnerabilities in the Linux kernel for Ubuntu 15.10. An incorrect locking fix caused a regression that broke graphics displays for Ubuntu 15.10 guests running 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 15.10
linux-image-4.2.0-30-generic - 4.2.0-30.36
linux-image-4.2.0-30-generic-lpae - 4.2.0-30.36
linux-image-4.2.0-30-lowlatency - 4.2.0-30.36
linux-image-4.2.0-30-powerpc-e500mc - 4.2.0-30.36
linux-image-4.2.0-30-powerpc-smp - 4.2.0-30.36
linux-image-4.2.0-30-powerpc64-emb - 4.2.0-30.36
linux-image-4.2.0-30-powerpc64-smp - 4.2.0-30.36

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