USN-6425-2: Samba regression

USN-6425-1 fixed vulnerabilities in Samba. Due to a build issue on Ubuntu
20.04 LTS, the update introduced regressions in macro handling and
possibly other functionality.

This update fixes the problem. We apologize for the inconvenience.

Original advisory details:

Sri Nagasubramanian discovered that the Samba acl_xattr VFS module
incorrectly handled read-only files. When Samba is configured to ignore
system ACLs, a remote attacker could possibly use this issue to truncate
read-only files. (CVE-2023-4091)

Andrew Bartlett discovered that Samba incorrectly handled the DirSync
control. A remote attacker with an RODC DC account could possibly use this
issue to obtain all domain secrets. (CVE-2023-4154)

Andrew Bartlett discovered that Samba incorrectly handled the rpcecho
development server. A remote attacker could possibly use this issue to
cause Samba to stop responding, resulting in a denial of service.
(CVE-2023-42669)

Kirin van der Veer discovered that Samba incorrectly handled certain RPC
service listeners. A remote attacker could possibly use this issue to cause
Samba to start multiple incompatible RPC listeners, resulting in a denial
of service. This issue only affected Ubuntu 22.04 LTS, and Ubuntu 23.04.
(CVE-2023-42670)