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Ubuntu Security Notice USN-1211-1
September 21, 2011

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

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

- Ubuntu 11.04

Summary:

Multiple kernel flaws have been fixed.

Software Description:
- linux: Linux kernel

Details:

It was discovered that the /proc filesystem did not correctly handle
permission changes when programs executed. A local attacker could hold open
files to examine details about programs running with higher privileges,
potentially increasing the chances of exploiting additional
vulnerabilities. (CVE-2011-1020)

Dan Rosenberg discovered that the X.25 Rose network stack did not correctly
handle certain fields. If a system was running with Rose enabled, a remote
attacker could send specially crafted traffic to gain root privileges.
(CVE-2011-1493)

Vasiliy Kulikov and Dan Rosenberg discovered that ecryptfs did not
correctly check the origin of mount points. A local attacker could exploit
this to trick the system into unmounting arbitrary mount points, leading to
a denial of service. (CVE-2011-1833)

It was discovered that Bluetooth l2cap and rfcomm did not correctly
initialize structures. A local attacker could exploit this to read portions
of the kernel stack, leading to a loss of privacy. (CVE-2011-2492)

It was discovered that GFS2 did not correctly check block sizes. A local
attacker could exploit this to crash the system, leading to a denial of
service. (CVE-2011-2689)

Fernando Gont discovered that the IPv6 stack used predictable fragment
identification numbers. A remote attacker could exploit this to exhaust
network resources, leading to a denial of service. (CVE-2011-2699)

The performance counter subsystem did not correctly handle certain
counters. A local attacker could exploit this to crash the system, leading
to a denial of service. (CVE-2011-2918)

Update instructions:

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

Ubuntu 11.04:
  linux-image-2.6.38-11-generic   2.6.38-11.50
  linux-image-2.6.38-11-generic-pae  2.6.38-11.50
  linux-image-2.6.38-11-omap      2.6.38-11.50
  linux-image-2.6.38-11-powerpc   2.6.38-11.50
  linux-image-2.6.38-11-powerpc-smp  2.6.38-11.50
  linux-image-2.6.38-11-powerpc64-smp  2.6.38-11.50
  linux-image-2.6.38-11-server    2.6.38-11.50
  linux-image-2.6.38-11-versatile  2.6.38-11.50
  linux-image-2.6.38-11-virtual   2.6.38-11.50

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:sup
  http://www.ubuntu.com/usn/usn-1211-1
  CVE-2011-1020, CVE-2011-1493, CVE-2011-1833, CVE-2011-2492,
  CVE-2011-2689, CVE-2011-2699, CVE-2011-2918

Package Information:
  https://launchpad.net/ubuntu/+source/linux/2.6.38-11.50