The bug is caused by sk_buff double free and cannot be triggered without xfrm6_tunnel module loaded. If you do not need to use the xfrm6_tunnel module, you can choose to blacklist it.
Upstream commit: http://git.kernel.org/linus/d0772b70 (v2.6.22-rc1) Statement: This issue did not affect the Linux kernel as shipped with Red Hat Enterprise Linux 6, and Red Hat Enterprise MRG. This has been addressed in Red Hat Enterprise Linux 5 via https://rhn.redhat.com/errata/RHSA-2012-0480.html. A future kernel update for Red Hat Enterprise Linux 4 may address this issue.
If you do not run applications that use xfrm6_tunnel, you can prevent the xfrm6_tunnel module from being loaded by creating (as the root user) a "/etc/modprobe.d/xfrm6_tunnel.conf" file, and adding the following line to it: blacklist xfrm6_tunnel This way, the xfrm6_tunnel module cannot be loaded accidentally. A reboot is not necessary for this change to take effect.
This issue has been addressed in following products: Red Hat Enterprise Linux 5 Via RHSA-2012:0480 https://rhn.redhat.com/errata/RHSA-2012-0480.html
Created kernel tracking bugs for this issue Affects: fedora-all [bug 818873]
This issue has been addressed in following products: Red Hat Enterprise Linux 5.6 EUS - Server Only Via RHSA-2012:0720 https://rhn.redhat.com/errata/RHSA-2012-0720.html