IT36729: FDC from xcsFreeMemFn in amqrmppa process reporting xecS_I_PRIVATE_MEMORY_ERROR during thread cleanup

APAR status

• Closed as program error.

Error description

• With IT34004 applied, a problem persists where an invalid
  pointer may still be accessed during thread cleanup operations.
  
  Failure data capture (FDC) records with the following
  characteristics may also be observed:
  
  Probe Id          :- XC130003
  Component     :- xehExceptionHandler
  Thread            :- nn    RemoteResponder
  MQM Function Stack
  ccxResponder
  rrxResponder
  ccxReceiveThreadFn
  ccxReceiveThreadCleanup
  cciEndConv
  rriAsyncConvControl
  rriFreeSess
  ccxStageFree
  xcsFFST
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Client or Channel applications on MQ version 9.2.0.2 with
  SHARECONV(1), that may experience network interruptions.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A network socket error in cciTcpSend function causes the socket
  to be closed and the ccxReceiveThreadCleanup function to perform
  cleanup tasks.
  IT34004 addressed the problem where a timing condition existed
  where some memory freed during the cleanup operation may be
  double freed at a later stage in the cleanup process. There
  remained a possibility the freed memory pointer could be
  accessed without first checking it was valid and so a code path
  existed where an attempt to access the pointer caused a segment
  violation or xecS_I_PRIVATE_MEMORY_ERROR error FDC to be
  captured.
  

Problem conclusion

• An extra check has been added to ensure the memory pointer is
  validated before use.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.12
  v9.1 LTS   9.1.0.9
  v9.2 LTS   9.2.0.3
  v9.x CD    9.2.3
  
  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

  5724H7271

Applicable component levels