png_set_unknown_chunks(png_structp png_ptr,
   png_infop info_ptr, png_unknown_chunkp unknowns, int num_unknowns)
{
   png_unknown_chunkp np;
   int i;

   if (png_ptr == NULL || info_ptr == NULL || num_unknowns == 0)
      return;

   np = (png_unknown_chunkp)png_malloc_warn(png_ptr,
       (png_uint_32)((info_ptr->unknown_chunks_num + num_unknowns) *
       png_sizeof(png_unknown_chunk)));
   if (np == NULL)
   {
      png_warning(png_ptr,
          "Out of memory while processing unknown chunk.");
      return;
   }

   png_memcpy(np, info_ptr->unknown_chunks,
       info_ptr->unknown_chunks_num * png_sizeof(png_unknown_chunk));
   png_free(png_ptr, info_ptr->unknown_chunks);
   info_ptr->unknown_chunks = NULL;

   for (i = 0; i < num_unknowns; i++)
   {
      png_unknown_chunkp to = np + info_ptr->unknown_chunks_num + i;
      png_unknown_chunkp from = unknowns + i;

      png_memcpy((png_charp)to->name, (png_charp)from->name,
          png_sizeof(from->name));
      to->name[png_sizeof(to->name)-1] = '\0';
      to->size = from->size;
      /* Note our location in the read or write sequence */
      to->location = (png_byte)(png_ptr->mode & 0xff);

      if (from->size == 0)
         to->data=NULL;
      else
      {
         to->data = (png_bytep)png_malloc_warn(png_ptr,
           (png_uint_32)from->size);
         if (to->data == NULL)
         {
            png_warning(png_ptr,
             "Out of memory while processing unknown chunk.");
            to->size = 0;
         }
         else
            png_memcpy(to->data, from->data, from->size);
      }
   }

   info_ptr->unknown_chunks = np;
   info_ptr->unknown_chunks_num += num_unknowns;
#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_UNKN;
#endif
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.