The signal implementation in the Linux kernel before 4.3.5 on powerpc platforms does not check for an MSR with both the S and T bits set, which allows local users to cause a denial of service (TM Bad Thing exception and panic) via a crafted application.
https://github.com/torvalds/linux/commit/d2b9d2a5ad5ef04ff978c9923d19730cb05efd55
https://bugzilla.redhat.com/show_bug.cgi?id=1326540
http://www.securitytracker.com/id/1035594
http://www.openwall.com/lists/oss-security/2016/04/13/1
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.3.5
http://rhn.redhat.com/errata/RHSA-2016-2584.html