LI75146: COMPILER ABEND WHEN MEMCMP HAS A NEGATIVE LENGTH

October 2009 Update for XL C/C++ for Linux, V10.1
June 2011 Update for XL C/C++ for Linux, V10.1
XL C/C++ for Linux Fix Pack 8 (January 2014 Update) for 10.1
August 2010 Update for XL C/C++ for Linux, V10.1
January 2011 Update for XL C/C++ for Linux, V10.1
January 2012 Update for XL C/C++ for Linux, V10.1
July 2012 Update for XL C/C++ for Linux, V10.1

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:

  IZ47922

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

Fix information

• Fixed component name

  XL C/C++ SLES10

• Fixed component ID

  5724U8300

Applicable component levels

• RA10 PSN IZ47922

     UP06/09/13