Re: [Boost-users] program_options: wild write

From: Will Bryant (will_at_[hidden])
Date: 2005-11-23 03:50:07

Merrill Cornish wrote:
> I've still got the problem that an illegal option value triggers Dr Watson.  I need to create a short example that I can post.
>   
Here's one to produce my segfault, which may or may not be the same as 
yours:

#include <boost/program_options.hpp>
#include <iostream>

int main(int argc, char* argv[])
{
    try
    {
        boost::program_options::options_description desc("Test");
        desc.add_options()("test", 
boost::program_options::value<std::string>(),
            "import the specified OBJ file and save it to MDLM format");
        std::cerr << desc;
        return 0;
    }
    catch (const std::exception& except)
    {
        std::cerr << except.what() << std::endl;
        return 1;
    }
}

As per my message the other day, this triggers a bug in 
options_description.cpp's format_paragraph function, which causes a 
segfault on linux with g++ 4.0.2 (and an assertion failure on Visual 
Studio 2005 beta 2); running it under valgrind 2.4.0 on linux produces:

==5197== Memcheck, a memory error detector for x86-linux.
==5197== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al.
==5197== Using valgrind-2.4.0, a program supervision framework for 
x86-linux.
==5197== Copyright (C) 2000-2005, and GNU GPL'd, by Julian Seward et al.
==5197== For more details, rerun with: -v
==5197==
Test:
  --test arg            import the specified OBJ file and save it to MDLM
                        format
==5197== Invalid read of size 2
==5197==    at 0x1B9ABB6E: 
__gnu_cxx::__pool<true>::_M_reclaim_block(char*, unsigned) (in 
/usr/lib/libstdc++.so.6.0.6)
==5197==    by 0x804A35C: __gnu_cxx::__mt_alloc<unsigned long, 
__gnu_cxx::__common_pool_policy<__gnu_cxx::__pool, true> 
 >::deallocate(unsigned long*, unsigned) (in /home/will/devel/a.out)
==5197==    by 0x804A39B: std::_Bvector_base<std::allocator<bool> 
 >::_M_deallocate() (in /home/will/devel/a.out)
==5197==    by 0x804A3B3: std::_Bvector_base<std::allocator<bool> 
 >::~_Bvector_base() (in /home/will/devel/a.out)
==5197==    by 0x804A40B: std::vector<bool, std::allocator<bool> 
 >::~vector() (in /home/will/devel/a.out)
==5197==    by 0x804A79A: 
boost::program_options::options_description::~options_description() (in 
/home/will/devel/a.out)
==5197==    by 0x8049863: main (in /home/will/devel/a.out)
==5197==  Address 0x8 is not stack'd, malloc'd or (recently) free'd
==5197==
==5197== Process terminating with default action of signal 11 (SIGSEGV)
==5197==  Access not within mapped region at address 0x8
==5197==    at 0x1B9ABB6E: 
__gnu_cxx::__pool<true>::_M_reclaim_block(char*, unsigned) (in 
/usr/lib/libstdc++.so.6.0.6)
==5197==    by 0x804A35C: __gnu_cxx::__mt_alloc<unsigned long, 
__gnu_cxx::__common_pool_policy<__gnu_cxx::__pool, true> 
 >::deallocate(unsigned long*, unsigned) (in /home/will/devel/a.out)
==5197==    by 0x804A39B: std::_Bvector_base<std::allocator<bool> 
 >::_M_deallocate() (in /home/will/devel/a.out)
==5197==    by 0x804A3B3: std::_Bvector_base<std::allocator<bool> 
 >::~_Bvector_base() (in /home/will/devel/a.out)
==5197==    by 0x804A40B: std::vector<bool, std::allocator<bool> 
 >::~vector() (in /home/will/devel/a.out)
==5197==    by 0x804A79A: 
boost::program_options::options_description::~options_description() (in 
/home/will/devel/a.out)
==5197==    by 0x8049863: main (in /home/will/devel/a.out)
==5197==
==5197== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 25 from 1)
==5197== malloc/free: in use at exit: 857654 bytes in 79 blocks.
==5197== malloc/free: 81 allocs, 2 frees, 858704 bytes allocated.
==5197== For counts of detected errors, rerun with: -v
==5197== searching for pointers to 79 not-freed blocks.
==5197== checked 1037872 bytes.
==5197==
==5197== LEAK SUMMARY:
==5197==    definitely lost: 0 bytes in 0 blocks.
==5197==      possibly lost: 8160 bytes in 2 blocks.
==5197==    still reachable: 849494 bytes in 77 blocks.
==5197==         suppressed: 0 bytes in 0 blocks.
==5197== Reachable blocks (those to which a pointer was found) are not 
shown.
==5197== To see them, rerun with: --show-reachable=yes
Segmentation fault

-- 
Will Bryant
http://carcino.gen.nz/
will_at_[hidden]
[phone]