DOS issue - DefaultUncaughtExceptionHandler needs to be set

[elkner]

Hmm, just played around with some loggers and found out, that JBoss does not set a DefaultUncaughtExceptionHandler (see Thread.setDefaultUncaughtExceptionHandler(...)).

The problem here is, that if an exception is not caught (e.g. NPE), it leads to the invocation of
ThreadGroup.uncaughtException(Thread t, Throwable e) which in turn leads to printing the stack trace line by line to stderr and thus each line triggers a log.error($line).

So if one e.g. has configured a more or less expensive logAppender (e.g. like the SMTPLogger), it may lead to a DOS. E.g. I triggered a single NPE in a SLSB, which resulted in ~ 1900 mails ...

So does anybody know, what one has to do, that the appropriate handler is set right on the start of jboss? Setting up an extra service for it seems a little bit to much overhead for such a simple thing ...

[elkner]

Found a solution by myself:

--- jboss-4.0.4RC1-src/system/src/main/org/jboss/system/server/ServerImpl.java.orig Mon Mar 20 23:38:02 2006
+++ jboss-4.0.4RC1-src/system/src/main/org/jboss/system/server/ServerImpl.java Mon Mar 20 23:45:07 2006
@@ -172,6 +172,16 @@
 // masqurade as Server.class (cause Impl is not really important)
 log = Logger.getLogger(Server.class);

+ // log uncaught errors as well - avoid DOS since System.err output gets
+ // logged line by line -
+ // see ThreadGroup.uncaughtException(Thread t, Throwable e)
+ Thread.setDefaultUncaughtExceptionHandler(new Thread
+ .UncaughtExceptionHandler() {
+ public void uncaughtException(Thread t, Throwable e) {
+ log.error("Uncaught exception in " + t.getName(), e);
+ }
+ }
+ );
 // Setup URL handlers - do this before initializing the ServerConfig
 initURLHandlers();
 config.initURLs();

[starksm64]

An NPE should not result in an uncaught exception. Create a jira issue describing how this occurs.
http://jira.jboss.com/jira/browse/EJBTHREE

[elkner]

Hmm, already fixed that stuff and have no ex. handy anymore. If I'm remember correctly, I created a Thread (more or less long running task) from within a bean and within the thread I got an NPE ...

[starksm64]

Ok, if your creating threads you are responsible for them behaving badly. I have created a feature request to configure a DefaultUncaughtExceptionHandler.
http://jira.jboss.com/jira/browse/JBAS-3022