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

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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 number

    IT21300

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7241

  • Reported release

    750

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-07-05

  • Closed date

    2017-09-05

  • Last modified date

    2017-09-05

  • 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

  • R750 PSY

       UP



Document information

More support for: WebSphere MQ
APAR / Maintenance

Software version: 7.5

Reference #: IT21300

Modified date: 05 September 2017


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