PH37470: MQ Z/OS: DATA CONVERSION FOR RFH/RFH2 HEADERS NEEDS TO BETTER HANDLE AN MQGET WITH A SHORT BUFFERLENGTH

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• During data conversion, when MQMD.Format is found to have
  "MQHRF" (MQFMT_RF_HEADER) or "MQHRF2" (MQFMT_RF_HEADER_2),
  CSQARFH is called. If the BufferLength specified on the MQGET
  is shorter than the length of the header, data conversion
  fails.  Normally, this situation is handled, and the
  application receives the expected reason code 2079
  MQRC_TRUNCATED_MSG_ACCEPTED.  If the header offset MQ is
  attempting to convert falls into a storage page with a
  different key or a page that has been freed, an ABEND0C4 will
  occur in CSQARFH.
  
  CSQARFH should be updated to to handle small but non-zero
  buffer lengths.
  

Local fix

• If the application is using a small BufferLength because it
  only wants to find the length of the message and does not want
  the data yet, specify a BufferLength of 0 for the MQGET. That
  value is already handled explicitly and will result in
  circumvention of the problem in CSQARFH plus increased
  performance, because the conversion of the buffer will be
  skipped completely.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 1 Modification 0 and                 *
  *                 Release 2 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: During conversion of an RFH1 or RFH2    *
  *                      header, if the message buffer is too    *
  *                      short to contain the entire header an   *
  *                      abend 0C4 or unexpected attempt to load *
  *                      module 'MQHRF' or 'MQHRF2' can occur.   *
  *                      The error only occurs in environments   *
  *                      that use the 31bit MQ conversion path   *
  *                      (for example: CICS, IMS).               *
  ****************************************************************
  While converting an RFH header, CSQARFH attempts to determine
  the length of the variable NameValue data in the header.
  When the buffer is not long enough, a reference can be made
  to storage beyond the end of the buffer leading to an abend 0C4
  if this storage cannot be accessed, or unexpected behaviour
  depending on the contents of the storage.
  

Problem conclusion

• CSQARFH is changed to correctly determine when the buffer is
  too small to contain the necessary fields.
  

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:

  UI79256 UI79257

Modules/Macros

• CSQARFH
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R100 PSY UI79257

     UP22/03/11 P F203

• R200 PSY UI79256

     UP22/03/11 P F203

Fix is available

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