The futex_wait function in kernel/futex.c in the Linux kernel before 2.6.37 does not properly maintain a certain reference count during requeue operations, which allows local users to cause a denial of service (use-after-free and system crash) or possibly gain privileges via a crafted application that triggers a zero count.
https://bugzilla.redhat.com/show_bug.cgi?id=1094455
http://rhn.redhat.com/errata/RHSA-2014-1763.html