The KEYS subsystem in the Linux kernel before 4.4 allows local users to gain privileges or cause a denial of service (BUG) via crafted keyctl commands that negatively instantiate a key, related to security/keys/encrypted-keys/encrypted.c, security/keys/trusted.c, and security/keys/user_defined.c.
https://usn.ubuntu.com/3798-2/
https://usn.ubuntu.com/3798-1/
https://github.com/torvalds/linux/commit/096fe9eaea40a17e125569f9e657e34cdb6d73bd
https://bugzilla.redhat.com/show_bug.cgi?id=1284450
https://access.redhat.com/errata/RHSA-2018:0181
https://access.redhat.com/errata/RHSA-2018:0152
https://access.redhat.com/errata/RHSA-2018:0151
http://www.openwall.com/lists/oss-security/2015/12/09/1
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00038.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00045.html
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00094.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00034.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00022.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00021.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00019.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00018.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00017.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00011.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00009.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00008.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00007.html