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IV96347: LOGIN HANGS TRYING TO WRITE TO /ETC/UTMP APPLIES TO AIX 7200-00 17/09/29 PTF PECHANGE

A fix is available

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • **************************************************************
    * USERS AFFECTED:
    * Systems running the AIX 7200-00 Technology Level
    * with bos.rte.libc at the 7.2.0.3 level.
      **************************************************************
    * ERROR DESCRIPTION:
    * In the latest SPs, all logins to AIX or VIOS LPARs via
    * telnet, ssh, or console may hang.  This can happen because a
    * lock on /etc/utmp is permanently held by a running process.
    *
    * This has been seen commonly with the 'screen' or 'init'
    * processes holding the lock.
    *
    * Killing all the processes that opened the file /etc/utmp ,
    * can free the lock and allow logins.
    * For example:
    *
    * # fuser -k /etc/utmp
    *
    * If the process cannot be killed (such as 'init'), then the
    * file can be renamed, allowing new logins to create and use
    * a new /etc/utmp file and succeed.
    * For example:
    *
    * # mv /etc/utmp /etc/utmp.bak
    *
    * Note: this will cause some commands such as 'who' and 'w'
    * to report incorrect information about users logged in to
    * the system.
    *
    * Note: These are only temporary workarounds, as the issue
    * can reoccur until the fix is applied and the system is
    * rebooted for the fix to take effect in all processes.
      **************************************************************
    * RECOMMENDATION:
    * Install APAR IV96347.
    * Prior to fix availability, an interim fix is available from
    * either
    * ftp://aix.software.ibm.com/aix/ifixes/iv96347/
    * https://aix.software.ibm.com/aix/ifixes/iv96347/
    * The ifix can be installed using Live Update (LU).
    * If LU is not used, installation of the ifix requires a
    * reboot.
      **************************************************************
    

Local fix

Problem summary

  • login sessions start to hang. In customer scenario init
    process while writing to /etc/utmp has taken a write lock
    and it is never released. Hence login sessions hang as they
    do not get lock to write /etc/utmp. This is caused because
    an uninitialized size is assigned to len value in lock
    structure
    

Problem conclusion

  • Initialize a size variable to proper value i.e size of lock
    structure before assigning this value to len variable
    in lock structure.
    

Temporary fix

  • *********
      * HIPER *
      *********
    

Comments

APAR Information

  • APAR number

    IV96347

  • Reported component name

    AIX V7.2

  • Reported component ID

    5765CD200

  • Reported release

    720

  • Status

    CLOSED PER

  • PE

    YesPE

  • HIPER

    YesHIPER

  • Submitted date

    2017-05-18

  • Closed date

    2017-05-18

  • Last modified date

    2017-10-05

  • APAR is sysrouted FROM one or more of the following:

    IV96177

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    AIX V7.2

  • Fixed component ID

    5765CD200

Applicable component levels

  • R720 PSY U878417

       UP17/10/05 I 1000 «

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Document Information

Modified date:
05 October 2017