The do_double_fault function in arch/x86/kernel/traps.c in the Linux kernel through 3.17.4 does not properly handle faults associated with the Stack Segment (SS) segment register, which allows local users to cause a denial of service (panic) via a modify_ldt system call, as demonstrated by sigreturn_32 in the linux-clock-tests test suite.
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00020.html
http://secunia.com/advisories/62336
https://github.com/torvalds/linux/commit/6f442be2fb22be02cafa606f1769fa1e6f894441