USN-2850-1: Linux kernel vulnerabilities
19 December 2015
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 15.04
Several security issues were fixed in the kernel.
- linux - Linux kernel
Felix Wilhelm discovered a race condition in the Xen paravirtualized drivers which can cause double fetch vulnerabilities. An attacker in the paravirtualized guest could exploit this flaw to cause a denial of service (crash the host) or potentially execute arbitrary code on the host. (CVE-2015-8550)
Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not perform sanity checks on the device’s state. An attacker could exploit this flaw to cause a denial of service (NULL dereference) on the host. (CVE-2015-8551)
Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not perform sanity checks on the device’s state. An attacker could exploit this flaw to cause a denial of service by flooding the logging system with WARN() messages causing the initial domain to exhaust disk space. (CVE-2015-8552)
Jann Horn discovered a ptrace issue with user namespaces in the Linux kernel. The namespace owner could potentially exploit this flaw by ptracing a root owned process entering the user namespace to elevate its privileges and potentially gain access outside of the namespace. (http://bugs.launchpad.net/bugs/1527374, CVE-2015-8709)
The problem can be corrected by updating your system to the following package versions:
- Ubuntu 15.04
- linux-image-3.19.0-42-generic - 3.19.0-42.48
- linux-image-3.19.0-42-generic-lpae - 3.19.0-42.48
- linux-image-3.19.0-42-lowlatency - 3.19.0-42.48
- linux-image-3.19.0-42-powerpc-e500mc - 3.19.0-42.48
- linux-image-3.19.0-42-powerpc-smp - 3.19.0-42.48
- linux-image-3.19.0-42-powerpc64-emb - 3.19.0-42.48
- linux-image-3.19.0-42-powerpc64-smp - 3.19.0-42.48
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.
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.