CVE-2017-2636 Red Hat Enterprise Linux Local Kernel Privilege Escalation Vulnerability.

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Race condition in drivers/tty/n_hdlc.c in the Linux kernel allows local users to gain privileges or cause a denial of service (double free) by setting the HDLC line discipline.

On successful exploitation it allows an attacker with an account on the local system to potentially elevate privileges.

No solution is available till date. All Red Hat customers running affected versions of the kernel are strongly recommended to update the kernel as soon as patches are available. Workaround:
The n_hdlc kernel module will be automatically loaded when an application attempts to use the HDLC line discipline from userspace.
The following command, run as root, will prevent accidental or intentional loading of the module. Red Hat Product Security believes this is a robust method to prevent accidental loading of the module, even by privileged users.

# echo "install n_hdlc /bin/true">> /etc/modprobe.d/disable-n_hdlc.conf

The system will need to be restarted if the n_hdlc modules are already loaded. In most circumstances, the n_hdlc kernel modules will be unable to be unloaded if in use and while any current process using this line discipline is required.

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