USN-1529-1: Linux kernel vulnerabilities

10 August 2012

Several security issues were fixed in the kernel.

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A flaw was discovered in the Linux kernel's macvtap device driver, which is
used in KVM (Kernel-based Virtual Machine) to create a network bridge
between host and guest. A privleged user in a guest could exploit this flaw
to crash the host, if the vhost_net module is loaded with the
experimental_zcopytx option enabled. (CVE-2012-2119)

An error was discovered in the Linux kernel's network TUN/TAP device
implementation. A local user with access to the TUN/TAP interface (which is
not available to unprivileged users until granted by a root user) could
exploit this flaw to crash the system or potential gain administrative
privileges. (CVE-2012-2136)

A flaw was found in how the Linux kernel's KVM (Kernel-based Virtual
Machine) subsystem handled MSI (Message Signaled Interrupts). A local
unprivileged user could exploit this flaw to cause a denial of service or
potentially elevate privileges. (CVE-2012-2137)

A flaw was found in the Linux kernel's Reliable Datagram Sockets (RDS)
protocol implementation. A local, unprivileged user could use this flaw to
cause a denial of service. (CVE-2012-2372)

Ulrich Obergfell discovered an error in the Linux kernel's memory
management subsystem on 32 bit PAE systems with more than 4GB of memory
installed. A local unprivileged user could exploit this flaw to crash the
system. (CVE-2012-2373)

It was discovered that hypervkvpd, which is distributed in the Linux
kernel, was not correctly validating the origin on Netlink messages. An
untrusted local user can cause a denial of service of Linux guests in
Hyper-V virtualization environments. (CVE-2012-2669)

Dan Rosenberg discovered flaws in the Linux kernel's NCI (Near Field
Communication Controller Interface). A remote attacker could exploit these
flaws to crash the system or potentially execute privileged code.
(CVE-2012-3364)

A flaw was discovered in the Linux kernel's epoll system call. An
unprivileged local user could use this flaw to crash the system.
(CVE-2012-3375)

Some errors where discovered in the Linux kernel's UDF file system, which
is used to mount some CD-ROMs and DVDs. An unprivileged local user could
use these flaws to crash the system. (CVE-2012-3400)

A flaw was discovered in the madvise feature of the Linux kernel's memory
subsystem. An unprivileged local use could exploit the flaw to cause a
denial of service (crash the system). (CVE-2012-3511)

Denys Fedoryshchenko discovered a flaw in the Linux kernel's TCP receive
processing for IPv4. A remote attacker could exploit this flaw to cause a
denial of service (kernel resource consumption) via a flood of SYN+FIN TCP
packets. (CVE-2012-6638)

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Update instructions

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

Ubuntu 12.04

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.

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