PM74689: 0C4 IN MVS31FRE WHEN FREEING A BUFFER IN THE I/O STORAGE POOL WHICH IS ALREADY FREED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• mvs31fre cannot tolerate an element passed in to free from the
  I/O pool structure, which does not have a proper alloc header
  and thus the pgm check. Underneath that, there is a double free
  for a buffer. During fclose processing, through the I/O peg a
  call is made to osfree. osfree+BC frees mbufptr->buffer  then
  later in the same routine osfree+EA frees fcb->savedbuf. When
  these two fields invalidly point to the same buffer, the
  double free occurs.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: C/C++ applications using fixed or variable   *
  *                 datasets with type=record and                *
  *                 multibuffering.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: C/C++ applications using type=record    *
  *                      datasets with multibuffering may see a  *
  *                      program check in mvs31fre.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  See problem description.
  

Problem conclusion

• The code was changed to
  fix the problem.
  

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:

  UK91402 UK91403

Modules/Macros

• CELHP074 CELHP082 CELQP074 CELQP082 EDC4004F
  EDC40050
  

Fix information

• Fixed component name

  LE C LIBRARY

• Fixed component ID

  568819805

Applicable component levels

• R770 PSY UK91402

     UP13/02/20 P F302

• R780 PSY UK91403

     UP13/02/20 P F302

Fix is available

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