The hashbin_delete function in net/irda/irqueue.c in the Linux kernel before 4.9.13 improperly manages lock dropping, which allows local users to cause a denial of service (deadlock) via crafted operations on IrDA devices.
https://github.com/torvalds/linux/commit/4c03b862b12f980456f9de92db6d508a4999b788
https://usn.ubuntu.com/3754-1/
http://www.debian.org/security/2017/dsa-3804
http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.13