IT29565: IBM MQ client app using MQCONNX to make an SSL connection fails with FDC from xehExceptionHandler with rriCopyMQSCO on the stack

APAR status

• Closed as program error.

Error description

• A native client application using MQCONNX to establish an SSL
  connection to the queue manager fails with a memory fault and
  writes an FDC like this:
  
  Probe Id          :- XC130031  [or XC130003]
  Component         :- xehExceptionHandler
  Major Errorcode   :- xecF_E_UNEXPECTED_SYSTEM_RC
  Comment1          :- Access Violation at address
                       0000000000000010 when writing
  
  Stack Backtrace:
  MSVCR110!memset+0xa0<NLN:487>
  mqe!rriCopyMQSCO+0x1d2<NLN:487>
  mqe!rriInitSess+0x1ac4<NLN:487>
  mqe!reqConnectChl+0x595<NLN:487>
  mqe!reqDoConnect+0xcb7<NLN:487>
  mqe!rreqMQCONNX+0x14f<NLN:487>
  mqe!tmzstMQCONNX+0x4d8<NLN:487>
  mqe!reqMQCONNX+0x55<NLN:487>
  mqe!MQCONNX_Client_Call+0xc1<NLN:487>
  mqe!zswMQCONNX_Client_Call+0x20d<NLN:487>
  
  MQM Function Stack
  MQQueueManager.Connect()
  UnmanagedNmqiMQ.MQCONNX(String,MQConnectOptions,Phconn,out in...
  UnmanagedNmqiMQ.MQCONNX(String,ref MQCNO,Hconn,Phconn,out int...
  MQCONNX
  MQCONNX
  trmzstMQCONNX
  reqDoConnect
  reqConnectChl
  rriInitSess
  rriCopyMQSCO
  xcsFFST
  

Local fix

• Disabling SSL or serializing MQCONNX/MQDISC between theads of
  the client application avoids the memory fault.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users with multi-threaded IBM MQ MQI client applications which
  use the MQSCO structure to control SSL parameters when
  connecting to an MQ queue manager.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  IBM MQ MQI client applications may use the MQSCO structure to
  control SSL configuration settings when establishing a secure
  connection to an MQ queue manager.  These SSL configuration
  settings can be altered by the client application only when
  there are no other SSL-secured connections.  If an application
  tries to change the SSL settings when another SSL-secured
  connection is active, MQCONNX will return completion code
  MQCC_WARNING and reason code MQRC_SSL_ALREADY_INITIALIZED.
  
  The MQI client code contained a timing window when one thread
  called MQDISC on the last active SSL-secured connection,, while
  at the same time another thread called MQCONNX to create a new
  SSL-secured connection.  An application with multiple threads
  independently creating and disconnecting SSL-secured connections
  to MQ could crash as a result of this timing window.
  

Problem conclusion

• The MQ code has been corrected to remove a timing window which
  could cause a crash when the last SSL-secured client connection
  is disconnecting in one thread while a new SSL-secured client
  connection is being established by a different thread.  Multiple
  client threads may safely call MQCONNX passing MQCNO, MQSCO and
  MQAIR structures to configure the SSL connection while other
  client threads are calling MQDISC on existing SSL connections.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.16
  v9.0 LTS   9.0.0.11
  v9.1 LTS   9.1.0.7
  v9.2 LTS   9.2.0.2
  
  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

  IBM MQ BASE MP

• Fixed component ID

  5724H7251

Applicable component levels