IT21300: amqzlaa0 process fails with memory exception SIGSEGV when activity trace is enabled

APAR status

• Closed as program error.

Error description

• The IBM MQ agent process amqzlaa0 ended with memory exception
  when generating activity trace.
  The FDC generated is likely to show the MQGETM call failing with
  MQRC_TRUNCATED_MSG_FAILED,
  followed by a SIGSEGV in the
  zsqAddByteStringATParameter/zsqATCallbackAfter/memcpy function.
  
  Excerpt from the FDC:
  
  Probe Id          :- XC130004
  Component         :- xehExceptionHandler
  Arith1            :- 11 (0xb)
  Comment1        :- SIGSEGV: address not mapped((nil))
  
  O/S Call Stack for current thread
  /opt/mqm/lib64/libmqmcs_r.so(xcsPrintStackForCurrentThread+0x3e)
  [0x2ad42387333e]
  /opt/mqm/lib64/libmqmcs_r.so(signalHandlerInternal+0x8d)[0x2ad42
  388bf6d]
  /opt/mqm/lib64/libmqmcs_r.so(PrepareDumpAreas+0xbce)[0x2ad42388a
  bee]
  /opt/mqm/lib64/libmqmcs_r.so(xcsFFSTFn+0x934)[0x2ad42388d1a4]
  /opt/mqm/lib64/libmqmcs_r.so(xehExceptionHandler+0x104e)[0x2ad42
  3888d0e]
  /lib64/libpthread.so.0(+0xf850)[0x2ad423fc1850]
  /lib64/libc.so.6(memcpy+0x15b)[0x2ad42445b35b]
  /opt/mqm/lib64/libmqml_r.so(zsqAddByteStringATParameter+0x145)[0
  x2ad4233aed65]
  /opt/mqm/lib64/libmqml_r.so(zsqATCallbackAfter+0x322)[0x2ad4233b
  edf2]
  /opt/mqm/lib64/libmqml_r.so(zsqMQGETM+0x55f)[0x2ad4233c73bf]
  /opt/mqm/bin/amqzlaa0[0x414d07]
  /opt/mqm/bin/amqzlaa0[0x417c77]
  /opt/mqm/bin/amqzlaa0[0x40958b]
  /opt/mqm/bin/amqzlaa0[0x40a83f]
  /opt/mqm/lib64/libmqmcs_r.so(+0x115fb3)[0x2ad4238dafb3]
  /lib64/libpthread.so.0(+0x7806)[0x2ad423fb9806]:
  /lib64/libc.so.6(clone+0x6d)[0x2ad4244b267d]
  
  MQM Function Stack
  zlaMainThread
  zlaProcessMessage
  zlaProcessMQIRequest
  zlaMQGETM
  zsqMQGETM
  zsqATCallbackAfter
  zsqAddByteStringATParameter
  xcsFFST
  
  MQM Trace History
  ...
  ----------} aqqReadMsgHdr rc=OK
  ---------} aqhLocateMessage rc=OK
  --------} aqhGetMessage rc=MQRC_TRUNCATED_MSG_FAILED
  --------{ aqsRecoverQOp
  --------} aqsRecoverQOp rc=OK
  -------} aqmGetMessage rc=MQRC_TRUNCATED_MSG_FAILED
  ------} apiGetMessage rc=MQRC_TRUNCATED_MSG_FAILED
  ...
  -----} kqiWaitForMessage rc=MQRC_TRUNCATED_MSG_FAILED
  ----} kpiMQGETM rc=OK
  ----{ zsqATCallbackAfter
  -----{ zsqAddCompCodeAndReasonToATGroup
  ------{
  ...
  -----} zsqAddCompCodeAndReasonToATGroup rc=OK
  ...
  -----{ zsqAddByteStringATParameter
  ------{ xcsGetMemFn
  ------} xcsGetMemFn rc=OK
  ------{ xcsFFST
  

Local fix

• NA
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users using asynchronous consume with activity trace enabled.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  This problem occurred because IBM MQ was trying to dereference a
  NULL pointer when generating activity trace in the
  MQGET(asynchronous consume) call.
  

Problem conclusion

• The MQ code has been modified to prevent MQ accessing the NULL
  pointer.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.5       7.5.0.9
  v8.0       8.0.0.8
  v9.0 CD    9.0.4
  v9.0 LTS   9.0.0.3
  
  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

  WMQ BASE MULTIP

• Fixed component ID

  5724H7241

Applicable component levels