CVE-2017-12762

A buffer overflow was found in the Linux kernel’s isdn_net_newslave() function in the /drivers/isdn/i4l/isdn_net.c file. An overflow happens when the user-controlled buffer is copied into a local buffer of constant size using strcpy() without a length check.

Mitigation

The ISDN kernel module is automatically loaded when the system boots and the ISDN service is present and enabled. The kernel modules can be prevented from being loaded by using system-wide modprobe rules. Run the following commands to blacklist the ISDN module, thus preventing them from loading:

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

On RHEL 6 execute the following commands as root to check if any isdn-related services are present:

# chkconfig --list | grep isdn

and disable them if they are:

#  chkconfig isdn off

(or use a name of another isdn-related service)