arch/x86/include/asm/pgtable.h in the Linux kernel before 3.6.2, when transparent huge pages are used, does not properly support PROT_NONE memory regions, which allows local users to cause a denial of service (system crash) via a crafted application.
https://github.com/torvalds/linux/commit/027ef6c87853b0a9df53175063028edb4950d476
https://bugzilla.redhat.com/show_bug.cgi?id=912898
http://www.openwall.com/lists/oss-security/2013/02/20/4
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.6.2