PI72792: MEMORY OVERLAY WHEN LOADING AND STORING BIT FIELD

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Loading and storing values from a bit field struct is causing a
  memory write overlay on memory past the end of the bit field.
  The issue occurs when loading and storing 4 bytes when only 3
  bytes should be updated.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users that have a bit field of three bytes   *
  *                 occupying the last three bytes of a bit      *
  *                 field container. For example:typedef struct  *
  *                 {  unsigned   bf1:6;  unsigned   bf2:2;      *
  *                 unsigned   bf3:24;} A;                       *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: The compiler is emitting a load/strore  *
  *                      instruction starting at offset 1 thus   *
  *                      accessing the byte following the bit    *
  *                      field. In most cases this does not      *
  *                      cause a problem since the byte          *
  *                      following the bit field is updated      *
  *                      with the same content it already has,   *
  *                      but when the bit field is at the end    *
  *                      of the address space or at the end of   *
  *                      the page this produces an 0C4 ABEND.    *
  ****************************************************************
  * RECOMMENDATION: Apply the provided PTF                       *
  *                                                              *
  ****************************************************************
  The compiler is producing bad code for sources with bit fields.
  

Problem conclusion

• Apply provided service.
  

Temporary fix

Comments

APAR Information

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

  PI64727

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

  UI42900

Modules/Macros

•    CCNECICS CCNECWI  CCNEDSCT CCNEDWRT CCNED211
  CCNEFILT CCNEHIFC CCNEMDEP CCNEOPTP CCNEP    CCNEPP   CCNETBY
  CCNMSGE  CCNMSGT
  

Fix information

• Fixed component name

  C/C++ FOR MVS

• Fixed component ID

  56551210A

Applicable component levels

• R791 PSY UI42900

     UP16/12/20 P F612

Fix is available

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