IT20676: Potential invalid memory access when using readahead to retrievenon-persistent messages

APAR status

• Closed as program error.

Error description

• An MQ client application retrieving non-persistent messages from
  a queue using the readahead functionality has the potential to
  make an invalid memory access
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of MQ client applications which use the
  readahead functionality to retrieve non-persistent messages from
  a queue.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A small timing window existed in the MQ channel code where an
  internal value representing the get message options of the
  consuming application could be accessed by the channel after
  being freed on another thread.
  
  This could theoretically cause the channel to use an invalid
  value for the get message options.
  
  This issue was detected internally by IBM through code analysis,
  and has not been observed in any known customer deployment.
  

Problem conclusion

• The MQ channel code within the queue manager has been updated to
  prevent this potential window for invalid memory access.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.7
  v9.0 CD    9.0.4
  v9.0 LTS   9.0.0.2
  
  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

  WMQ BASE MULTIP

• Fixed component ID

  5724H7251

Applicable component levels

• R800 PSY

     UP