USN-1211-1: Linux kernel vulnerabilities

Ubuntu Security Notice USN-1211-1

21st September, 2011

linux vulnerabilities

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

  • Ubuntu 11.04


Multiple kernel flaws have been fixed.

Software description

  • linux - Linux kernel


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.

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)

A flaw was found in the Linux kernel's /proc/*/*map* interface. A local,
unprivileged user could exploit this flaw to cause a denial of service.

Ben Hutchings discovered several flaws in the Linux Rose (X.25 PLP) layer.
A local user or a remote user on an X.25 network could exploit these flaws
to execute arbitrary code as root. (CVE-2011-4914)

Update instructions

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

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

To update your system, please follow these instructions:

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


CVE-2011-1020, CVE-2011-1493, CVE-2011-1833, CVE-2011-2492, CVE-2011-2689, CVE-2011-2699, CVE-2011-2918, CVE-2011-3637, CVE-2011-4914