IT40776: NullPointerException observed when a security exit is being called concurrently on multiple threads.

APAR status

• Closed as program error.

Error description

• After upgrading from MQ 9.2.0.4 to MQ 9.2.0.5, when an MQ
  classes for Java/JMS client side security exit is called by two
  different threads concurrently, for example in the scenario:
  
    - when an application requests that a new connection be
  established to the queue manager, where the exit rejects the
  connection attempt causing it to be closed, which results in the
  security exit being called again
  
    - when the queue manager sends a response back to the client
  to close the current conversation, which results in the security
  exit being called
  
  a race condition takes place in the processing of the MQCD
  object which is passed to the security exit.
  This results in a NullPointerException being generated by the MQ
  classes for Java/JMS, of the form:
  
  java.lang.NullPointerException
   at com.ibm.mq.exits.MQCD.readFromBuffer(MQCD.java:4009)
   at
  com.ibm.mq.jmqi.remote.exit.NativeExitDefinition.unpackMQCD(Nati
  veExitDefinition.java:341)
   at
  com.ibm.mq.jmqi.remote.exit.NativeExitDefinition.invoke(NativeEx
  itDefinition.java:419)
   at
  com.ibm.mq.jmqi.remote.exit.RemoteExitChain.termExit(RemoteExitC
  hain.java:1463)
   at
  com.ibm.mq.jmqi.remote.exit.RemoteExitChain.termExits(RemoteExit
  Chain.java:1432)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnection.disconnect(RemoteCo
  nnection.java:1112)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnection.removeSession(Remot
  eConnection.java:882)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteSession.disconnect(RemoteSessi
  on.java:1744)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnectionSpecification.getSes
  sion(RemoteConnectionSpecification.java:365)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnectionPool.getSession(Remo
  teConnectionPool.java:161)
   at
  com.ibm.mq.jmqi.remote.api.RemoteFAP.jmqiConnect(RemoteFAP.java:
  1748)
   at
  com.ibm.mq.jmqi.remote.api.RemoteFAP.jmqiConnect(RemoteFAP.java:
  1274)
   at
  com.ibm.mq.ese.jmqi.InterceptedJmqiImpl.jmqiConnect(InterceptedJ
  mqiImpl.java:377)
   at com.ibm.mq.ese.jmqi.ESEJMQI.jmqiConnect(ESEJMQI.java:562)
   at
  com.ibm.msg.client.wmq.internal.WMQConnection.<init>(WMQConnecti
  on.java:357)
   at
  com.ibm.msg.client.wmq.factories.WMQConnectionFactory.createV7Pr
  oviderConnection(WMQConnectionFactory.java:8470)
   at
  com.ibm.msg.client.wmq.factories.WMQConnectionFactory.createProv
  iderConnection(WMQConnectionFactory.java:7909)
   at
  com.ibm.msg.client.jms.admin.JmsConnectionFactoryImpl._createCon
  nection(JmsConnectionFactoryImpl.java:325)
   at
  com.ibm.msg.client.jms.admin.JmsConnectionFactoryImpl.createConn
  ection(JmsConnectionFactoryImpl.java:243)
   at
  com.ibm.mq.jms.MQConnectionFactory.createCommonConnection(MQConn
  ectionFactory.java:6038)
   at
  com.ibm.mq.jms.MQQueueConnectionFactory.createQueueConnection(MQ
  QueueConnectionFactory.java:111)
   at
  com.ibm.mq.jms.MQQueueConnectionFactory.createConnection(MQQueue
  ConnectionFactory.java:202)
  at myApplication.myMethod()
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the MQ classes for Java and MQ
  classes for JMS, which are configured to utilise client side
  security exits.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  There are scenarios where a security exit can end up being run
  on two different threads concurrently for the same connection to
  the queue manager.
  One such scenario was introduced by APAR IT38158:
  
  https://www.ibm.com/support/pages/apar/IT38158
  
  which addressed a connection handle leak when a security exit
  rejected a new connection attempt to the queue manager.  The
  queue manager may request that the newly initiated connection be
  closed before the application thread has closed it, following
  the rejection by the security exit.
  
  This resulted in a race condition associated with the access to
  the MQCD object which is passed to the security exit.  If a
  certain timing condition was reached, this may have resulted in
  the a NullPointerException being generated by the MQ classes for
  Java, for example of the form:
  
  java.lang.NullPointerException
   at com.ibm.mq.exits.MQCD.readFromBuffer(MQCD.java:4009)
   at
  com.ibm.mq.jmqi.remote.exit.NativeExitDefinition.unpackMQCD(Nati
  veExitDefinition.java:341)
   at
  com.ibm.mq.jmqi.remote.exit.NativeExitDefinition.invoke(NativeEx
  itDefinition.java:419)
   at
  com.ibm.mq.jmqi.remote.exit.RemoteExitChain.termExit(RemoteExitC
  hain.java:1463)
   at
  com.ibm.mq.jmqi.remote.exit.RemoteExitChain.termExits(RemoteExit
  Chain.java:1432)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnection.disconnect(RemoteCo
  nnection.java:1112)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnection.removeSession(Remot
  eConnection.java:882)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteSession.disconnect(RemoteSessi
  on.java:1744)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnectionSpecification.getSes
  sion(RemoteConnectionSpecification.java:365)
   at
  com.ibm.mq.jmqi.remote.impl.RemoteConnectionPool.getSession(Remo
  teConnectionPool.java:161)
   at
  com.ibm.mq.jmqi.remote.api.RemoteFAP.jmqiConnect(RemoteFAP.java:
  1748)
   at
  com.ibm.mq.jmqi.remote.api.RemoteFAP.jmqiConnect(RemoteFAP.java:
  1274)
   at
  com.ibm.mq.ese.jmqi.InterceptedJmqiImpl.jmqiConnect(InterceptedJ
  mqiImpl.java:377)
   at com.ibm.mq.ese.jmqi.ESEJMQI.jmqiConnect(ESEJMQI.java:562)
   at
  com.ibm.msg.client.wmq.internal.WMQConnection.<init>(WMQConnecti
  on.java:357)
   at
  com.ibm.msg.client.wmq.factories.WMQConnectionFactory.createV7Pr
  oviderConnection(WMQConnectionFactory.java:8470)
   at
  com.ibm.msg.client.wmq.factories.WMQConnectionFactory.createProv
  iderConnection(WMQConnectionFactory.java:7909)
   at
  com.ibm.msg.client.jms.admin.JmsConnectionFactoryImpl._createCon
  nection(JmsConnectionFactoryImpl.java:325)
   at
  com.ibm.msg.client.jms.admin.JmsConnectionFactoryImpl.createConn
  ection(JmsConnectionFactoryImpl.java:243)
   at
  com.ibm.mq.jms.MQConnectionFactory.createCommonConnection(MQConn
  ectionFactory.java:6038)
   at
  com.ibm.mq.jms.MQQueueConnectionFactory.createQueueConnection(MQ
  QueueConnectionFactory.java:111)
   at
  com.ibm.mq.jms.MQQueueConnectionFactory.createConnection(MQQueue
  ConnectionFactory.java:202)
   at myApplication.myMethod()
  
   In this example the NullPointerException was thrown back to the
  application, and the connection attempt failed.
  
   NOTE: This APAR does not affect MQ 9.1
  

Problem conclusion

• The MQ classes for Java/JMS have been updated such that the
  access to the MQCD object passed to the security exit on the two
  threads is now thread safe.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  
  v9.2 LTS   9.2.0.6
  v9.3 LTS   9.3.0.1
  v9.x CD    9.3.1
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  MQ WINDOWS V7

• Fixed component ID

  5724H7220

Applicable component levels