VM65086: PROBLEMS WITH SETTING PROMISCUOUS MODE ON A VIRTUAL NIC

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Problems with incorrectly setting promiscuous mode can cause
  duplicate packets to be delivered to a guest coupled to a LAN
  or VSWITCH.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: VM guests using virtual NIC devices in       *
  *                 promiscuous mode to monitor network          *
  *                 activity.                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  The customer observed that a Linux guest using promiscuous mode
  with a virtual NIC interface was recording duplicate frames.
  After reviewing the promiscuous mode logic, we suspected that
  the same NIDBK was being processed multiple times for this
  LANBK.  We provided an exec to check the LANBK promiscuous
  interface chain against the promiscuous mode counter.  The
  customer discovered that each time the guest performed a
  shutdown and restart (shutdown -r now) the counter increased
  while the user NIDBK remained on the chain.  This points to a
  problem in the routine that activates promiscuous mode for a
  given NIDBK.
  

Problem conclusion

• Entry point HCPNDFPM activates promiscuous mode for a given
  NIDBK.  Closer inspection confirms that it is not protected
  against updating the LANBK chain for a NIDBK that was already
  active in promiscuous mode.  This problem is corrected by
  testing for NIDPRMAD already set at entry to HCPNDFPM (for the
  set option).  If NIDPRMAD is already set, this NIDBK is
  already on the LANPROM chain (making this a redundant request).
  

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:

  UM33580 UM33581 UM33582

Modules/Macros

• HCPNDF
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R540 PSY UM33580

     UP11/12/20 P 1202

• R610 PSY UM33581

     UP13/04/25 P 1301

• R620 PSY UM33582

     UP12/11/20 P 1202

Fix is available

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