The Network Lock Manager (NLM) protocol implementation in the NFS client functionality in the Linux kernel before 3.0 allows local users to cause a denial of service (system hang) via a LOCK_UN flock system call.
ftp.osuosl.org/pub/linux/kernel/v3.0/ChangeLog-3.0
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=0b760113a3a155269a3fba93a409c640031dd68f
rhn.redhat.com/errata/RHSA-2011-1212.html
www.openwall.com/lists/oss-security/2011/06/23/6
bugzilla.redhat.com/show_bug.cgi?id=709393
github.com/torvalds/linux/commit/0b760113a3a155269a3fba93a409c640031dd68f