[png-mng-implement] png_write_info() crash

[Cas E. <cas...@pl...>]

this is my code:

void pngWrite( char *file_name, int width, int height, unsigned char *buffer )
{
 FILE *fp;
 png_structp png_ptr;
 png_infop info_ptr;
 png_color_8 sig_bit;
 int i;
 int j;
 int k;
 int row;
 png_bytep *row_pointers;
 
 fopen_s( &fp, file_name, "wb");

 png_ptr = png_create_write_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );

 if( png_ptr == NULL )
 {
  fclose( fp );
  return;
 }

 info_ptr = png_create_info_struct( png_ptr );

 if( info_ptr == NULL )
 {
  fclose( fp );
  png_destroy_write_struct( &png_ptr, NULL );
  return;
 }

 if( setjmp( png_ptr->jmpbuf ) )
 {
  png_destroy_write_struct( &png_ptr, &info_ptr );
  fclose( fp );
  return;
 }
 
 png_init_io( png_ptr, fp );
 
 png_set_IHDR( png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
      PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE );
  
 sig_bit.red = 8;
 sig_bit.green = 8;
 sig_bit.blue = 8;
 sig_bit.alpha = 8;
 png_set_sBIT( png_ptr, info_ptr, &sig_bit );

 png_write_info( png_ptr, info_ptr );

 png_set_packing( png_ptr );
 
 row_pointers = ( png_bytep* )malloc( sizeof( png_bytep ) * height );

 for( row = 0; row < height; row++ )
 {
  row_pointers[row] = ( png_bytep )malloc( width * 4 );
 }
 
 if( row_pointers == NULL )
 {
  return;
 }
 
 k = 0;
 i = 0;
 
 while( i < height )
 {
  j = 0;
  while( j < width * 4 )
  {
   row_pointers[i][j+0] = buffer[k];
   k++;
   row_pointers[i][j+1] = buffer[k];
   k++;
   row_pointers[i][j+2] = buffer[k];
   k++;
   row_pointers[i][j+3] = buffer[k];
   k++;
   
   j += 4;
  }
  i++;
 }
 
 png_write_image(png_ptr, row_pointers);
 png_write_end(png_ptr, info_ptr);
 png_destroy_write_struct(&png_ptr, &info_ptr);
 fclose(fp);
 return;
}

my program crashes at png_write_info. what could be wrong?