[USN-2691-1] Linux kernel vulnerabilities

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==========================================================================
Ubuntu Security Notice USN-2691-1
July 28, 2015

linux vulnerabilities
==========================================================================

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

- Ubuntu 15.04

Summary:

Several security issues were fixed in the kernel.

Software Description:
- linux: Linux kernel

Details:

Andy Lutomirski discovered a flaw in the Linux kernel's handling of nested
NMIs (non-maskable interrupts). An unprivileged local user could exploit
this flaw to cause a denial of service (system crash) or potentially
escalate their privileges. (CVE-2015-3290)

Colin King discovered a flaw in the add_key function of the Linux kernel's
keyring subsystem. A local user could exploit this flaw to cause a denial
of service (memory exhaustion). (CVE-2015-1333)

Andy Lutomirski discovered a flaw that allows user to cause the Linux
kernel to ignore some NMIs (non-maskable interrupts). A local unprivileged
user could exploit this flaw to potentially cause the system to miss
important NMIs resulting in unspecified effects. (CVE-2015-3291)

Andy Lutomirski and Petr Matousek discovered that an NMI (non-maskable
interrupt) that interrupts userspace and encounters an IRET fault is
incorrectly handled by the Linux kernel. An unprivileged local user could
exploit this flaw to cause a denial of service (kernel OOPs), corruption,
or potentially escalate privileges on the system. (CVE-2015-5157)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 15.04:
linux-image-3.19.0-25-generic 3.19.0-25.26
linux-image-3.19.0-25-generic-lpae 3.19.0-25.26
linux-image-3.19.0-25-lowlatency 3.19.0-25.26
linux-image-3.19.0-25-powerpc-e500mc 3.19.0-25.26
linux-image-3.19.0-25-powerpc-smp 3.19.0-25.26
linux-image-3.19.0-25-powerpc64-emb 3.19.0-25.26
linux-image-3.19.0-25-powerpc64-smp 3.19.0-25.26

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. If
you use linux-restricted-modules, you have to update that package as
well to get modules which work with the new kernel version. Unless you
manually uninstalled the standard kernel metapackages (e.g. linux-generic,
linux-server, linux-powerpc), a standard system upgrade will automatically
perform this as well.

References:
http://www.ubuntu.com/usn/usn-2691-1
CVE-2015-1333, CVE-2015-3290, CVE-2015-3291, CVE-2015-5157

Package Information:
https://launchpad.net/ubuntu/+source/linux/3.19.0-25.26