IZ47922: COMPILER ABEND WHEN MEMCMP HAS A NEGATIVE LENGTH

May 2009 PTF for XL C for AIX, V10.1
November 2009 PTF for XL C/C++ for AIX, V10.1
October 2010 PTF for XL C/C++ for AIX, V10.1
October 2010 PTF for XL C for AIX, V10.1
May 2012 PTF for XL C/C++ for AIX, V10.1
January 2013 PTF for XL C for AIX, V10.1
January 2013 PTF for XL C/C++ for AIX, V10.1
XL C/C++ for AIX Fix Pack 18 (July 2013 PTF) for 10.1
XL C/C++ for AIX Fix Pack 19 (October 2013 PTF) for 10.1
XL C/C++ for AIX Fix Pack 21 (October 2015 PTF) for 10.1
XL C for AIX Fix Pack 21 (October 2015 PTF) for 10.1
August 2009 PTF for XL C for AIX, V10.1
August 2009 PTF for XL C/C++ for AIX, V10.1
November 2009 PTF for XL C for AIX, V10.1
March 2010 PTF for XL C for AIX, V10.1
March 2010 PTF for XL C/C++ for AIX, V10.1
April 2010 PTF for XL C for AIX, V10.1
April 2010 PTF for XL C/C++ for AIX, V10.1
June 2010 PTF for XL C/C++ for AIX, V10.1
June 2010 PTF for XL C for AIX, V10.1
February 2011 PTF for XL C for AIX, V10.1
May 2011 PTF for XL C/C++ for AIX, V10.1
May 2011 PTF for XL C for AIX, V10.1
October 2011 PTF for XL C/C++ for AIX, V10.1
October 2011 PTF for XL C for AIX, V10.1
February 2012 PTF for XL C for AIX, V10.1
February 2012 PTF for XL C/C++ for AIX, V10.1
May 2012 PTF for XL C for AIX, V10.1
September 2012 PTF for XL C for AIX, V10.1
September 2012 PTF for XL C/C++ for AIX, V10.1
XL C for AIX Fix Pack 18 (July 2013 PTF) for 10.1
XL C for AIX Fix Pack 19 (October 2013 PTF) for 10.1
May 2009 PTF for XL C/C++ for AIX, V10.1
XL C for AIX Fix Pack 20 (October 2014 PTF) for 10.1
XL C/C++ for AIX Fix Pack 20 (October 2014 PTF) for 10.1

APAR status

• Closed as program error.

Error description

• xlCcode will abend with a memcmp that has a negative length
  under some cases.  This is a simplified test case is as follows:
  ---
  #include <string.h>
  
  char *a1, *a2;
  
  int bar1(void);
  int bar2(void);
  
  int main(void) {
    if (memcmp(a1, a2, -2)) {
      bar1();
    } else {
      bar2();
    }
    return 0;
  }
  ---
  
  Compile Line:
  xlC -c -O2 test.cpp
  (Also occurs in 64 bit mode)
  

Local fix

• n/a
  

Problem summary

• Users of memcmp() with negative size value (or
  equivalently, large unsigned value) that are
  compiling at -O2 or higher are affected by this issue.
  
  There is a defect in the compiler inline code of
  the memcmp() builtin for large unsigned value.
  

Problem conclusion

• The code that expands the memcmp() builtin
  does not handle well negative length values (large
  unsigned values).  We fixed it by adding additional range
  check code so that we don't do inline expansion for
  this case.
  

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:

  LI75105 LI75146

Fix information

• Fixed component name

  XL C AIX

• Fixed component ID

  5724U8000

Applicable component levels