sound/core/hrtimer.c in the Linux kernel before 4.4.1 does not prevent recursive callback access, which allows local users to cause a denial of service (deadlock) via a crafted ioctl call.
https://github.com/torvalds/linux/commit/2ba1fe7a06d3624f9a7586d672b55f08f7c670f3
https://bugzilla.redhat.com/show_bug.cgi?id=1311570
http://www.ubuntu.com/usn/USN-2967-2
http://www.ubuntu.com/usn/USN-2967-1
http://www.ubuntu.com/usn/USN-2932-1
http://www.ubuntu.com/usn/USN-2931-1
http://www.ubuntu.com/usn/USN-2930-3
http://www.ubuntu.com/usn/USN-2930-2
http://www.ubuntu.com/usn/USN-2930-1
http://www.ubuntu.com/usn/USN-2929-2
http://www.ubuntu.com/usn/USN-2929-1
http://www.securityfocus.com/bid/83382
http://www.openwall.com/lists/oss-security/2016/01/19/1
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.4.1
http://www.debian.org/security/2016/dsa-3503
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00038.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00045.html
http://lists.opensuse.org/opensuse-security-announce/2016-03/msg00094.html