Bug #88172 AbandonedConnectionCleanupThread does not handle SecurityException

Description:
The AbandonedConnectionCleanupThread calls Thread.setContextClassLoader in a static block
which may throw a SecurityException if a SecurityManager is in place.

This can prevent the driver class from instantiating in tomcat with the
-security flag enabled.

Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "setContextClassLoader")
        at java.security.AccessControlContext.checkPermission(AccessControlContext.java:472)
        at java.security.AccessController.checkPermission(AccessController.java:884)
        at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
        at java.lang.Thread.setContextClassLoader(Thread.java:1474)
        at com.mysql.jdbc.AbandonedConnectionCleanupThread$1.newThread(AbandonedConnectionCleanupThread.java:50)
        at java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor.java:619)
        at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:932)
        at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1367)

How to repeat:
Run
  Class.forName("com.mysql.jdbc.Driver")  from a tomcat application when
tomcat is run with the -security flag.

Same in test class with a security.policy file that dis-allows setContextClassLoader

Suggested fix:
Trap the exception 
Running with the thread classloader is better than not loading at all.

Hello Stephen,

Thank you for the bug report.
Verified based on internal discussion with dev's.

Thanks,
Chiranjeevi.

Posted by developer:
 
Thread.setContextClassLoader isn't the only operation that can trigger an AccessControlException; even reading system properties can. Avoiding the exception in AbandonedConnectionCleanupThread alone isn’t sufficient for the driver to work.

A better option would be to include the necessary grants in the conf/catalina.policy file. As of Connector/J 9.4.0, the following permissions allow minimal usage of the driver, but others may be needed
depending on the features in use:
- permission java.util.PropertyPermission "com.mysql.cj.disableAbandonedConnectionCleanup", "read";
- permission java.util.PropertyPermission "javax.net.*", "read";
- permission java.lang.RuntimePermission "setContextClassLoader";
- permission java.net.SocketPermission "*:*", "connect,resolve";
Permissions can also be granted on a per-jar basis, so I recommend defining a dedicated section for the Connector/J JAR file.

That said, keep in mind that SecurityManager has been deprecated in Java 17 and is expected to be removed in a future Java release. Because of this, it’s possible that this issue may never be addressed.