USN-2908-4: Linux kernel regression

Ubuntu Security Notice USN-2908-4

26th 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 version:

Ubuntu 15.10:: linux-image-4.2.0-30-powerpc-smp

4.2.0-30.36; linux-image-4.2.0-30-powerpc64-smp

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-powerpc64-emb

4.2.0-30.36; linux-image-4.2.0-30-generic-lpae

4.2.0-30.36; linux-image-4.2.0-30-generic

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

LP: 1548587

Source: USN-2908-4: Linux kernel regression

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