Re: [Boost-bugs] [Boost C++ Libraries] #4635: segmentation fault in text_oarchive::save_binary()

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #4635: segmentation fault in text_oarchive::save_binary()
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-03-21 06:39:54

#4635: segmentation fault in text_oarchive::save_binary()
---------------------------------------------+------------------------------
  Reporter:  Mark Heuser <mlheuser@…>        |       Owner:  ramey        
      Type:  Bugs                            |      Status:  new          
 Milestone:  To Be Determined                |   Component:  serialization
   Version:  Boost 1.43.0                    |    Severity:  Problem      
Resolution:                                  |    Keywords:               
---------------------------------------------+------------------------------

Comment (by Aliaksei Plashchanski <alekseyploschanskiy@…>):

 I met the same issue, i debugged and found that problem is in
 implementation base64_from_binary. Access violation appears in file
 transform_width.hpp.
 When iterator points to the last valid byte (addr+len-1) and algorithm
 need one more byte to complete missing bits - it increments iterator and
 read after buffer.

 {{{
 template<class Base, int BitsOut, int BitsIn, class CharType>
 CharType transform_width<Base, BitsOut, BitsIn, CharType>::fill(){
     CharType retval = 0;
     unsigned int missing_bits = BitsOut;
     for(;;){
         unsigned int bcount;
         if(! m_bufferfull){
             m_buffer = * this->base_reference();  !!! access to byte
 *(addr+len)
             m_bufferfull = true;
             bcount = BitsIn;
         }
         else
             bcount = BitsIn - m_displacement;
         unsigned int i = (std::min)(bcount, missing_bits);
         // shift interesting bits to least significant position
         unsigned int j = m_buffer >> (bcount - i);
         // strip off uninteresting bits
         // (note presumption of two's complement arithmetic)
         j &= ~(-(1 << i));
         // append then interesting bits to the output value
         retval <<= i;
         retval |= j;
         missing_bits -= i;
         if(0 == missing_bits)
             break;
         // note: suspect that this is not invoked for borland 5.51
         ++(this->base_reference());
         m_bufferfull = false;
     }
     return retval;
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4635#comment:3>
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