IT26218: Access Violation FDC reported with Probe Id XC130031 in functionxcsRequestThreadMutexSem.

APAR status

• Closed as program error.

Error description

• Initially a failure data capture (FDC) record  is generated,
  with the following Probe Id, Component, and Function Stack:
  Probe Id          :- CO000003
  Component         :- ccxAllocMem
  Major Errorcode   :- rrcE_BAD_PARAMETER
  Probe Description :- AMQ6125: An internal IBM MQ error has
  occurred.
  
  MQM Function Stack
  cciReceiveThread
  ccxReceiveThreadFn
  cciProcessOne
  cciReceiveOne
  cciSendHeartbeat
  ccxAllocMem
  xcsFFST
  
  Moments later, an Access Violation FDC record is generated, with
  the following Probe Id, Component, and Function Stack:
  Probe Id          :- XC130031
  Component         :- xehExceptionHandler
  Probe Description :- AMQ6109: An internal IBM MQ error has
  occurred.
  Comment1          :- Access Violation at address
  0000000000000008 when reading.
  .
  MQM Function Stack
  cciReceiveThread
  ccxReceiveThreadFn
  cciProcessOne
  cciReceiveOne
  cciSendHeartbeat
  ccxFreeMem
  xcsRequestThreadMutexSem
  xcsFFST
  

Local fix

• Disable heartbeating on the SVRCONN channel
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of clients which connect via
  server-connection (SVRCONN) channels and have heartbeating
  enabled.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  Due to a coding error, when freeing a memory buffer used for the
  sending of heartbeat flows, a small timing window existed where
  the client could attempt to access an invalid memory address.
  This resulted in an access violation on Microsoft Windows, or a
  SIGSEGV on UNIX platforms.
  
  It was possible for the timing window to occur at either the
  client or queue manager side of the channel.
  

Problem conclusion

• The MQ client logic, and the queue manager channel logic, have
  been updated to prevent this invalid memory access.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.7
  v9.1 CD    9.1.3
  v9.1 LTS   9.1.0.2
  
  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 M/P

• Fixed component ID

  5724H7261

Applicable component levels