The MITRE CVE dictionary describes this issue as:
crypto/ghash-generic.c in the Linux kernel before 3.1 allows local users to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact by triggering a failed or missing ghash_setkey function call, followed by a (1) ghash_update function call or (2) ghash_final function call, as demonstrated by a write operation on an AF_ALG socket.
Find out more about CVE-2011-4081 from the
MITRE CVE dictionary dictionary and
This issue did not affect the Linux kernels as shipped with Red Hat Enterprise Linux 4, and 5 as they did not include support for the GHASH message digest algorithm. This has been addressed in Red Hat Enterprise Linux 6, and MRG via https://rhn.redhat.com/errata/RHSA-2012-0350.html, and https://rhn.redhat.com/errata/RHSA-2012-0010.html.