IT37861: xtmTimerThread might fail to release memory when it ends

APAR status

• Closed as program error.

Error description

• A possible race condition exists, in which the thread had freed
  the block containing a handle needed for un-initialization, then
  read the handle from that block again.  Given that other threads
  in the process could immediately allocate and use that block, it
  is therefore not safe to read the handle variable from it, after
  it has been freed.  In the rare case that the handle has become
  invalid for use, then some memory allocated earlier on the
  thread will not be freed.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of MQ on AIX or Solaris platforms.
  
  
  Platforms affected:
  AIX, Solaris SPARC, Solaris x86-64
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A block had been freed, but a handle variable was then being
  read from that block, at a time when it was not safe to do so.
  

Problem conclusion

• The IBM MQ code has been corrected so that the block is freed
  only after the timer thread has finished reading data from it.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.11
  
  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