Ubuntu Security Notice 3160-1 - CAI Qian discovered that shared bind mounts in a mount namespace exponentially added entries without restriction to the Linux kernel's mount table. A local attacker could use this to cause a denial of service. It was discovered that a race condition existed in the procfs environ_read function in the Linux kernel, leading to an integer underflow. A local attacker could use this to expose sensitive information. Various other issues were also addressed.
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Ubuntu Security Notice USN-3160-1
December 20, 2016
linux vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 14.04 LTS
Summary:
Several security issues were fixed in the kernel.
Software Description:
- linux: Linux kernel
Details:
CAI Qian discovered that shared bind mounts in a mount namespace
exponentially added entries without restriction to the Linux kernel's mount
table. A local attacker could use this to cause a denial of service (system
crash). (CVE-2016-6213)
It was discovered that a race condition existed in the procfs
environ_read function in the Linux kernel, leading to an integer
underflow. A local attacker could use this to expose sensitive
information (kernel memory). (CVE-2016-7916)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 14.04 LTS:
linux-image-3.13.0-106-generic 3.13.0-106.153
linux-image-3.13.0-106-generic-lpae 3.13.0-106.153
linux-image-3.13.0-106-lowlatency 3.13.0-106.153
linux-image-3.13.0-106-powerpc-e500 3.13.0-106.153
linux-image-3.13.0-106-powerpc-e500mc 3.13.0-106.153
linux-image-3.13.0-106-powerpc-smp 3.13.0-106.153
linux-image-3.13.0-106-powerpc64-emb 3.13.0-106.153
linux-image-3.13.0-106-powerpc64-smp 3.13.0-106.153
linux-image-generic 3.13.0.106.114
linux-image-generic-lpae 3.13.0.106.114
linux-image-lowlatency 3.13.0.106.114
linux-image-powerpc-e500 3.13.0.106.114
linux-image-powerpc-e500mc 3.13.0.106.114
linux-image-powerpc-smp 3.13.0.106.114
linux-image-powerpc64-emb 3.13.0.106.114
linux-image-powerpc64-smp 3.13.0.106.114
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:
http://www.ubuntu.com/usn/usn-3160-1
CVE-2016-6213, CVE-2016-7916
Package Information:
https://launchpad.net/ubuntu/+source/linux/3.13.0-106.153