Local socket access to MariaDB does not work anymore after update to version 10.0.30

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Environment

SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)
SUSE Linux Enterprise Server 12 Service Pack 1 (SLES 12 SP1)

Situation

After a maintenance update of MariaDB to version 10.0.30 build 25.1 a connection to the database via local (AF_UNIX) sockets is not possible anymore.

Resolution

This issue has been fixed with build 28.1 of MariaDB 10.0.30:

SLES 12 SP2: https://download.suse.com/Download?buildid=S2wtOhZHd9c~
SLES 12 SP1: https://download.suse.com/Download?buildid=GLm1T5mrCww~

As a quick workaround, manually setting the correct permissions of /var/run/mysql and restarting MariaDB restores connectivity:

chmod 755 /var/run/mysql
systemctl restart mysql

This needs to be done after every reboot as /var/run is a symlink to /run which is located on a ramdisk.

Cause

The MariaDB start script was hardened to reduce the default permissions of created files to the minimum. Due to an oversight, the script does not set the correct permissions for /var/run/mysql after it creates the directory. Subsequently, MariaDB cannot create its socket when it runs as a user other than root.

Additional Information

Disclaimer

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