PK20978: RECORD STRUCTURE FTP TRANSFER CAN CAUSE BUFFER OVERRUN

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• .
  FTP operations specifying a record structure transfer require
  the sending system to scan for x'FF' bytes in the source file
  and substitute a two byte escape sequence.  With some
  combinations of record sizes and data content, this can cause
  the reformatted data to overlay original data that has not yet
  been processed.  This in turn causes the sender to go into a
  loop of repeated escape sequences which can then overlay other
  data not in the buffer area.
                                                                 .
  Record structure transfers are requested by a
    STRUCTURE RECORD     (can be abbreviated to STR R)
  command before the transfer request (GET, PUT, MGET or MPUT).
  For a failure to occur, the original file must have multiple
  x'FF' bytes in it.
                                                                 .
  Other symptoms:
                                                                 .
     Examination of a resultant dump will show an 180K area of
     storage that at some point becomes mostly x'FF' values with
     some other byte appearing occasionally.  This pattern
     continues well past the 180K area.  For FTP clients
     performing a PUT request, this area will be in private
     storage and will eventually overlay Language Environment
     control blocks.  For FTP servers processing a GET request,
     this area will be in ECSA.
  .
     May see an abend0c4 in IEAVRTI0 in load module IEANUC01
  .
     This may also manifest itself as an abend U4088 with reason
     code 7A in module EZAFTPLC.
  .
  

Local fix

• .
   (None)
                                                                 .
  Keywords:
                                                                 .
    ZOSFTP U4082 ABENDU4082 S0C4 ABENDS0C4 CSM CSA STRU XLMT
    EZAFTPLC U4088 4088 ABENDU4088 71 0000007A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release 7 IP: FTP         *
  ****************************************************************
  * PROBLEM DESCRIPTION: FTP over runs buffer area when using    *
  *                      STRU R and source file contains         *
  *                      untranslatable data (code points or     *
  *                      bytes).                                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  FTP operations specifying a record structure transfer require
  the sending system to scan for x'FF' bytes in the source file
  and substitute a two byte escape sequence.  This expansion
  was not taken into account by the buffer management code in
  FTP. As a result the buffer can be over run with extraneous
  escape characters.
  
  This problem can occur on both the FTP client and the FTP
  server when they are processing outbound data containing
  untranslatable data.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• FTP code has been modified to handle expansion while processing
  files using the STRucture R subcommand or RECord subcommand.
  
  * Cross Reference between External and Internal Names
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK13220 PK26464

Modules/Macros

• EZAFTPTO
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R170 PSY UK13220

     UP06/04/27 P F604 Ž

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.