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IT06884: MQ encounters SIGSEGV with probe ID XC130003 while deregistering a subscriber.

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APAR status

  • Closed as program error.

Error description

  • MQ reports SIGSEGV from kqiTopicDeregisterSubscriber while
    deregistering a subscriber.
    
    A failure data capture (FDC) record with probe id XC130003 is
    observed, with HALT6109 and SIGSEGV: address not mapped(0x2000).
    The call stack is as follows:
    
    O/S Call Stack for current thread
    /opt/mqm/mqxr/bin/../../lib64/libmqmcs_r.so(xcsPrintStackForCurr
    entThread+0x6e)[0x20085b6a2a6]
    /opt/mqm/mqxr/bin/../../lib64/libmqmcs_r.so(signalHandlerInterna
    l+0x50)[0x20085b8355c]
    /opt/mqm/mqxr/bin/../../lib64/libmqmcs_r.so(PrepareDumpAreas+0xc
    80)[0x20085b81ffc]
    /opt/mqm/mqxr/bin/../../lib64/libmqmcs_r.so(xcsFFSTFn+0x1124)[0x
    20085b85010]
    /opt/mqm/mqxr/bin/../../lib64/libmqmcs_r.so(xehExceptionHandler+
    0x27c)[0x20085b7f65c]
    [0x20095daf720]
    /opt/mqm/mqxr/bin/../../lib64/libmqml_r.so(kqiTopicDeregisterSub
    scriber+0x81a)[0x200865106da]
    /opt/mqm/mqxr/bin/../../lib64/libmqml_r.so(kqiCloseTopic+0xa8a)[
    0x200863fa58a]
    /opt/mqm/mqxr/bin/../../lib64/libmqml_r.so(kqiCloseIt+0x90c)[0x2
    0086335700]
    /opt/mqm/mqxr/bin/../../lib64/libmqml_r.so(kpiMQCLOSE+0x30e)[0x2
    0086336272]
    /opt/mqm/mqxr/bin/../../lib64/libmqml_r.so(zsqMQCLOSE+0x2f6)[0x2
    00864db872]
    /opt/mqm/lib64/amqzif_r(zifMQCLOSE+0x15a)[0x20084f3172a]
    /opt/mqm/mqxr/bin/../../lib64/libmqzi_r.so(zstMQCLOSE+0x61a)[0x2
    0086032e8a]
    /opt/mqm/lib64/libmqds_r.so(MQCLOSE+0xa2)[0x20084f0c542]
    /opt/mqm/mqxr/bin/../../lib64/libmqe_r.so(+0x432e60)[0x2008541de
    60]
    /opt/mqm/mqxr/bin/../../java/lib64/libmqjbnd.so(Java_com_ibm_mq_
    jmqi_local_internal_base_Native_MQCLOSE+0x176)[0x20084d488ae]
    
    MQM Function Stack
    MQCLOSE
    zstMQCLOSE
    zifMQCLOSE
    zsqMQCLOSE
    kpiMQCLOSE
    kqiCloseIt
    kqiCloseTopic
    kqiTopicDeregisterSubscriber
    xcsFFST
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users using WMQ 7.5 onwards with a publish/subscribe
    configuration where subscriptions are added/removed dynamically.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    A timing window existed within the publish/subscribe
    deregistration code, which could cause memory to be accessed
    after it had already been freed or reallocated. If encountered,
    this resulted in the SIGSEGV FDC from
    kqiTopicDeregisterSubscriber.
    

Problem conclusion

  • Extra checking has been introduced while removing the topic link
    and subscription to avoid this illegal memory access.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.5       7.5.0.8
    v8.0       8.0.0.7
    v9.0 CD    9.0.2
    v9.0 LTS   9.0.0.1
    
    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

    IT06884

  • 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

    2015-02-02

  • Closed date

    2016-12-12

  • Last modified date

    2017-06-01

  • 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

[{"Line of Business":{"code":"LOB36","label":"IBM Automation"},"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.5"}]

Document Information

Modified date:
13 September 2021