What is Badlock?
Please see this article from Red Hat for an overview of the vulnerability.
How can I test my system to see if I’m vulnerable?
Run this script:
curl -s http://kb.eclipseinc.com/files/badlock-test.sh | sh
It will generate a report similar to the following if your system is vulnerable:
WARNING: The installed version of samba server (4.2.3-12.el7_2) is vulnerable to BADLOCK and should be upgraded! It is also enabled and/or running. Please update the package and restart the service. See https://access.redhat.com/articles/2243351 and https://access.redhat.com/security/vulnerabilities/badlock for more information.
How do I patch my system?
Install Red Hat updates. If you don’t want to install all of the updates, you can optionally install only the samba updates:
yum update samba* service smb restart