IBM Support

IT20676: Potential invalid memory access when using readahead to retrievenon-persistent messages

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APAR status

  • Closed as program error.

Error description

  • An MQ client application retrieving non-persistent messages from
    a queue using the readahead functionality has the potential to
    make an invalid memory access
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of MQ client applications which use the
    readahead functionality to retrieve non-persistent messages from
    a queue.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    A small timing window existed in the MQ channel code where an
    internal value representing the get message options of the
    consuming application could be accessed by the channel after
    being freed on another thread.
    
    This could theoretically cause the channel to use an invalid
    value for the get message options.
    
    This issue was detected internally by IBM through code analysis,
    and has not been observed in any known customer deployment.
    

Problem conclusion

  • The MQ channel code within the queue manager has been updated to
    prevent this potential window for invalid memory access.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.7
    v9.0 CD    9.0.4
    v9.0 LTS   9.0.0.2
    
    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

    IT20676

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7251

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-05-19

  • Closed date

    2017-05-31

  • Last modified date

    2017-07-06

  • 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

    5724H7251

Applicable component levels

  • R800 PSY

       UP

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Document Information

Modified date:
06 July 2017