IT26389: MQ client application reports memory access exception in ChannelReceive thread.

APAR status

• Closed as program error.

Error description

• MQ 9.0.5.0 application encounters a memory access exception (e.g
  SIGSEGV) and a First Data Capture (FDC) record with the
  following data:
  
  Thread            :- nn    ChannelReceive
  Major Errorcode   :- STOP
  Arith1            :- 11 (0xb)
  Comment1          :- SIGSEGV: address not mapped(0x34)
  
  With the following MQ function stack:
  
  MQM Function Stack
      ccxReceiveThreadFn
      cciProcessOne
      cciReceiveOne
      xcsFFST
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  A very small timing window exists that can affect MQ Client
  applications.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A small timing window in the MQ client code could allow a buffer
  to be incorrectly freed, causing a SIGSEGV in the ChannelReceive
  thread.
  

Problem conclusion

• Additional checks and diagnostics have been implemented to
  ensure the buffer is not freed whilst in use.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 CD    9.1.2
  v9.1 LTS   9.1.0.3
  
  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 M/P

• Fixed component ID

  5724H7261

Applicable component levels

• R905 PSY

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