USN-5825-2: PAM regressions

USN-5825-2: PAM regressions

USN-5825-1 fixed vulnerabilities in PAM. Unfortunately that update was
incomplete and could introduce a regression. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

It was discovered that PAM did not correctly restrict login from an IP
address that is not resolvable via DNS. An attacker could possibly use this
issue to bypass authentication.
Source: USN-5825-2: PAM regressions