IZ91501: SEGFAULT WHEN THROWING IN VECTOR

January 2011 PTF for XL C/C++ for AIX, V11.1
May 2011 PTF for XL C/C++ for AIX, V11.1
August 2011 PTF for XL C/C++ for AIX, V11.1
November 2011 PTF for XL C/C++ for AIX, V11.1
January 2012 PTF for XL C/C++ for AIX, V11.1
April 2012 PTF for XL C/C++ for AIX, V11.1
July 2012 PTF for XL C/C++ for AIX, V11.1
October 2012 PTF for XL C/C++ for AIX, V11.1
February 2013 PTF for XL C/C++ for AIX, V11.1
XL C/C++ for AIX Fix Pack 14 (May 2013 PTF) for 11.1
XL C/C++ for AIX Fix Pack 15 (August 2013 PTF) for 11.1
XL C/C++ for AIX Fix Pack 16 (November 2013 PTF) for 11.1
XL C/C++ for AIX Fix Pack 17 (February 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 18 (May 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 19 (August 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 20 (November 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 21 (April 2015 PTF) for 11.1
XL C/C++ for AIX Fix Pack 22 (September 2015 PTF) for 11.1
XL C/C++ for AIX Fix Pack 23 (March 2016 PTF) for 11.1
XL C/C++ for AIX Fix Pack 24 (September 2016 PTF) for 11.1

APAR status

• Closed as program error.

Error description

• The following reduced test case segfaults if compiled with xlC
  on AIX, but runs correctly if compiled with g++ on AIX.
  
  $cat vec_throw_test.cpp
  #include <vector>
  #include <iostream>
  #include <stdexcept>
  
  using namespace std;
  
  static int n;
  
  class A
  {
  public:
      A()
      {
          me = n++;
          cout << "A() me=" << me << endl;
      }
      A(const A & x)
      {
          me = n++;
          cout << "A(A) me=" << me << ", x=" << x.me << endl;
          if ( me==13 )
              throw runtime_error("constructor failure");
      }
      const A & operator=(const A & x)
      {
          cout << "A=A me=" << me << ", x=" << x.me << endl;
          return *this;
      }
      ~A()
      {
          cout << "~A me=" << me << endl;
      }
  
      int me;
  };
  
  int main()
  {
      try
      {
      vector<A> a_vec;
      a_vec.reserve(10);
      A a;
      for (size_t i=0; i<15; ++i)
      {
          cout << "create " << i << endl;
          a_vec.push_back(a);
          cout << "vec=[";
          for (size_t j=0; j<a_vec.size(); ++j)
              cout << " " << a_vec[j].me;
          cout << " ]" << endl;
      }
      }
      catch ( const exception & x )
      {
          cout << "caught exception: " << x.what() << endl;
      }
      return 0;
  }
  
  
  
  $xlC vec_throw_test.cpp
  $./a.out
  ....
  ....
  Memory Fault
  

Local fix

• N/A
  

Problem summary

• PROBLEM DESCRIPTION: When a throw occurs in a user copy ctor
  when insertion causes a vector to relocate and grow, an
  unitialized pointer is used when cleaning up the partially
  constructed vector.
  
  USERS AFFECTED: std::vector on aix.
  

Problem conclusion

• The vector pointer is now initialized. Apply recommended
  service.
  

Temporary fix

Comments

APAR Information

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

  IZ81882

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

Fix information

• Fixed component name

  XL C/C++ AIX

• Fixed component ID

  5724X1300

Applicable component levels