The I/O implementation for block devices in the Linux kernel before 2.6.33 does not properly handle the CLONE_IO feature, which allows local users to cause a denial of service (I/O instability) by starting multiple processes that share an I/O context.
https://github.com/torvalds/linux/commit/b69f2292063d2caf37ca9aec7d63ded203701bf3
https://github.com/torvalds/linux/commit/61cc74fbb87af6aa551a06a370590c9bc07e29d9
https://bugzilla.redhat.com/show_bug.cgi?id=796829
http://www.ubuntu.com/usn/USN-1411-1
http://www.ubuntu.com/usn/USN-1410-1
http://www.ubuntu.com/usn/USN-1408-1
http://www.securitytracker.com/id?1027086
http://www.openwall.com/lists/oss-security/2012/02/23/5
http://www.debian.org/security/2012/dsa-2469
http://secunia.com/advisories/48842
http://secunia.com/advisories/48545
http://rhn.redhat.com/errata/RHSA-2012-0531.html
http://rhn.redhat.com/errata/RHSA-2012-0481.html
http://marc.info/?l=bugtraq&m=139447903326211&w=2
http://lists.opensuse.org/opensuse-security-announce/2012-05/msg00013.html