PI73778: WMQ ABEND0C4 CSQXBPQY DURING GSK_SECURE_SOCKET_WRITE PROCESSING

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Change Team finds failure occurred in an gsk_secure_socket_write
  SSL I/O module CSQXQIOC issued an cciBufferOutput call via
  routine cciSKWRite. The buffered I/O functions in csqxccib were
  called for cciBufferOutput, bufferManage, and bufferResize. As
  part of the bufferResize processing a call was made to
  ccxAllocMem to obtain storage for the re-sized buffer before a
  csqx_bpqy_get_header query call to retrieve the buffer pool
  header. Query buffer pool module csqxbpqy handled the call,
  initially setting up addressability to control blocks such as
  the DWA (addressed off the channel initiator's XEB control
  block) however the DWA pointer in the XEB can not be relied upon
  during SSL processing (in this case containing a null pointer)
  During lock group processing a compare/swap instruction was
  employed to set the lock in the pool header. As the pool header
  was addressed off of the DWA the CS failed with the abend
  reported here.
  ADDITIONAL SYMPTOMS :
  ABEND0C4 and/or ABEND5C6 - 00E70052
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of IBM MQ for z/OS Version 9 Release 0             *
  * Modification 0.                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Message CSQX153E CSQXSERV SSL server subtask ended           *
  * abnormally,                                                  *
  * reason=0C4000-00000004, during SSL send processing.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * None                                                         *
  ****************************************************************
  During SSL send processing module csqxqioc issues a
  cciBufferOutput call from routine cciSKWrite. The buffered i/o
  functions in csqxccib are called for cciBufferOutput,
  cciBufferManage and, as pSSLSENDBUFFER is null, bufferResize to
  obtain an SSL send buffer. A suitable buffer is found on the
  free chain and re-used. If a suitable buffer had not been found
  fresh storage would have been obtained on a 4k boundary for a
  new buffer pool.
  A csqx_bpqy_get_header call is then issued by bufferResize to
  locate the buffer pool header, passing the address of the buffer
  just obtained. Module csqxbpqy first sets up addressability to
  critical control blocks such as the DWA, which it addresses off
  the channel initiator XEB control block. However the DWA pointer
  in the XEB can not be relied upon during SSL processing, and in
  this case contains a null pointer, so the DWA is based on
  low-core storage.
  The pool header for this re-used buffer does not start on a 4k
  boundary, and can not be found by rounding down the passed
  buffer address, so csqxbpqy has to scan all the buffer chains to
  locate the passed buffer, and it's corresponding pool header. As
  part of this scan processing, lock_group is called and uses a
  compare and swap instruction to set the lock in the pool header.
  As the pool header is addressed off the DWA, the compare and
  swap fails with the reported ABEND0C4.
  
  CSQX153E !QMGR CSQXSERV SSL server subtask ended abnormally,
  TCB=xxxxxxxx reason=0C4000-00000004
  

Problem conclusion

• Query buffer pool module csqxbpqy is updated to address the
  DWA by other means when the pointer to it in the XEB is zero.
  

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:

  UI45092

Modules/Macros

• CSQXBPQY none
  

Fix information

• Fixed component name

  MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R000 PSY UI45092

     UP17/03/30 P F703

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.