Ubuntu Security Notice 2908-1 - 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. 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. Various other issues were also addressed.
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==========================================================================Ubuntu Security Notice USN-2908-1
February 22, 2016
linux vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 15.10
Summary:
Several security issues were fixed in the kernel.
Software Description:
- linux: Linux kernel
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 4.2.0-30.35
linux-image-4.2.0-30-generic-lpae 4.2.0-30.35
linux-image-4.2.0-30-lowlatency 4.2.0-30.35
linux-image-4.2.0-30-powerpc-e500mc 4.2.0-30.35
linux-image-4.2.0-30-powerpc-smp 4.2.0-30.35
linux-image-4.2.0-30-powerpc64-emb 4.2.0-30.35
linux-image-4.2.0-30-powerpc64-smp 4.2.0-30.35
After a standard system update you need to reboot your computer to make
all the necessary changes.
ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.
References:
https://www.ubuntu.com/usn/usn-2908-1
CVE-2013-4312, CVE-2015-8785, CVE-2016-1575, CVE-2016-1576,
CVE-2016-2069
Package Information:
https://launchpad.net/ubuntu/+source/linux/4.2.0-30.35