IT21247: SIGSEGV in zfuLdapGetUserDN reported by FDC with probe ID XC130004

APAR status

• Closed as program error.

Error description

• Queue manager becomes unavailable to client connections
  sometimes when using LDAP for authentication.
  
  Three FDCs are seen:
  1.
  
  Probe Id          :- XC130004
  Component         :- xehExceptionHandler
  Comment1          :- SIGSEGV: address not mapped(0x20)
  
  MQM Function Stack ends with:
    gpiAuthenticateUser
    zfu_as_AuthenticateUser
    zfuVerifyLdapPw
    zfuVerifyLdapPwMain
    zfuLdapGetUserDn
    xcsFFST
  
  2.
  
  Probe Id          :- XC130003
  Application Name  :- MQM
  Component         :- xehExceptionHandler
  Comment1          :- SIGSEGV: address not mapped((nil))
  
  O/S Call Stack for current thread contains:
    libmqmcs_r.so(xehExceptionHandler+0x965)
    libpthread.so.0(+0xf710)
    libmqmcs_r.so(xcsRequestMutexSemFn+0x90)
    libmqmr_r.so(rriDeleteStatusEntry+0x2d1)
    libmqmr_r.so(rriWriteCompMsg+0x33e)
  
  MQM Function Stack ends with:
    rriAsyncConvControl
    rriFreeSess
    rriWriteCompMsg
    rriDeleteStatusEntry
    xcsFFST
  
  3.
  
  Probe Id          :- XC514090
  Component         :- xlsRWMutexRequest
  Major Errorcode   :- xecL_W_LONG_LOCK_WAIT
  
  MQM Function Stack ends with
    gpiAuthenticateUser
    zfu_as_AuthenticateUser
    xlsRWMutexRequest
    xcsFFST
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Queue managers that use an LDAP repository (via an AUTHINFO
  object) to contain their users and groups.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  The MQ Object authority manager (OAM) was not robust in the case
  of memory exception failures within its lower layers or its
  dependency libraries.  The OAM was capable of handling the
  memory exception but failed to release the mutexes it held.  As
  a result, subsequent unrelated operations requiring those
  mutexes would hang.
  

Problem conclusion

• The code in the MQ OAM has been corrected to ensure that, when
  handling a memory exception, it will release its mutexes to
  prevent future hangs of unrelated operations.
  
  An additional fix is included, to ensure that, for secure LDAP
  connections on Windows, the correct GSKit libraries are first in
  the PATH at the time the LDAP libraries are called to connect to
  the LDAP server.  This removes a reason for connect failures, in
  the case where there is a global installation of GSKit available
  on the PATH, of an incompatible version to the one required by
  the MQ installation.  When this problem is visible, it causes a
  different reason code (usually 2063) to be returned from MQ API
  calls where the reason code ought to be 2035.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  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

  IBM MQ APPL M20

• Fixed component ID

  5725S1400

Applicable component levels

• R800 PSY

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