The robust futex implementation in the Linux kernel before 2.6.28 does not properly handle processes that make exec system calls, which allows local users to cause a denial of service or possibly gain privileges by writing to a memory location in a child process.
https://bugzilla.redhat.com/show_bug.cgi?id=771764
http://www.openwall.com/lists/oss-security/2012/05/08/1
http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.28