LI76633: BAD STACKPROTECT WITH VARIABLE LENGTH ARRAY

XL C/C++ for Linux Fix Pack 9 (August 2013 Update) for 11.1
June 2012 Update for XL C/C++ for Linux, V11.1
October 2012 Update for XL C/C++ for Linux, V11.1
XL C/C++ for Linux Fix Pack 8 (June 2013 Update) for 11.1

APAR status

• Closed as program error.

Error description

• When using the -qstackprotect feature, the system is throwing
  the stack smash error incorrectly in a function containing a
  variable length array.
  
  
     ===== Example Output =====
  
  $ ./a.out
  *** stack smashing detected ***: program terminated
  IOT/Abort trap (core dumped)
  $
  

Local fix

• N/A
  

Problem summary

• PROBLEM DESCRIPTION:
  After defining a variable length array, the stack pointer is
  updated to increase the size of the stack.  When loading the
  stack canary word at the end of a function, the offset used
  assumed that the stack pointer did not change, resulting in
  loading an incorrect value.
  
  USERS AFFECTED:
  Stack protect (-qstackprotect) users with source code
  containing variable length arrays.
  

Problem conclusion

• Stack protect feature was corrected, and now loads the canary
  word from the correct location.
  

Temporary fix

Comments

APAR Information

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

  IV09886

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

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5724X1400

Applicable component levels

• RB10 PSN IV09886

     UP06/09/13