IT37974: MQ REST web server ends after receiving SIGSEGV after running internal program amqoampx

APAR status

• Closed as program error.

Error description

• When an internal MQ program such as amqoampx runs from the MQ
  REST web server, the receipt of a SIGCHLD signal in the parent
  process when that child process ends is handled on the thread
  that started the program, and there is a race condition in which
  a trace counter can be incremented too many times.
  
  The trace counter was incremented too many times, and this
  resulted in a SIGSEGV from the trace routines.
  
  When the REST web server is the parent process, then the SIGSEGV
  results in javacore output files.  The javacore files show that
  the C code executing at the time was in an IBM MQ C library,
  most probably ibmqmcs_r.so..
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue is most likely to affect users who use the MQ REST
  web server, and who are using AUTHENMD(OS) or AUTHENMD(PAM) to
  obtain authentication via OS or PAM.
  
  
  Platforms affected:
  AIX, IBM iSeries, Linux on x86-64, Linux on zSeries, Solaris
  SPARC, Solaris x86-64
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  The subroutine that handled the SIGCHLD signal was attempting to
  write to the MQ internal trace table for that thread, but it had
  interrupted the running of an MQ thread that was writing to the
  same table at the time it was interrupted.  The subroutine that
  handled the SIGCHLD signal should not have attempted to write
  anything to this table.
  

Problem conclusion

• The IBM MQ code has been changed to ensure that a SIGCHLD
  handler that runs in this way does not attempt to write to the
  trace table, thus avoiding the problem.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.11
  v9.2 LTS   9.2.0.5
  v9.x CD    9.2.5
  
  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