Red Hat Security Advisory 2017-0892-01 – The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix: A race condition flaw was found in the N_HLDC Linux kernel driver when accessing n_hdlc.tbuf list that can lead to double free. A local, unprivileged user able to set the HDLC line discipline on the tty device could use this flaw to increase their privileges on the system.