 png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
   int max_palette_length, num, i;
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_colorp pal_ptr;
 #endif

   png_debug(1, "in png_handle_PLTE");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before PLTE");

   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid PLTE after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }

   else if (png_ptr->mode & PNG_HAVE_PLTE)
      png_error(png_ptr, "Duplicate PLTE chunk");

   png_ptr->mode |= PNG_HAVE_PLTE;

   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
   {
      png_warning(png_ptr,
        "Ignoring PLTE chunk in grayscale PNG");
      png_crc_finish(png_ptr, length);
      return;
   }
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
   if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
   {
      png_crc_finish(png_ptr, length);
      return;
   }
#endif

   if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
   {
      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
      {
         png_warning(png_ptr, "Invalid palette chunk");
         png_crc_finish(png_ptr, length);
         return;
      }

      else
      {
         png_error(png_ptr, "Invalid palette chunk");
       }
    }
 
   /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
    num = (int)length / 3;
 
   /* If the palette has 256 or fewer entries but is too large for the bit
    * depth, we don't issue an error, to preserve the behavior of previous
    * libpng versions. We silently truncate the unused extra palette entries
    * here.
    */
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      max_palette_length = (1 << png_ptr->bit_depth);
   else
      max_palette_length = PNG_MAX_PALETTE_LENGTH;

   if (num > max_palette_length)
      num = max_palette_length;

 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
    {
      png_byte buf[3];

      png_crc_read(png_ptr, buf, 3);
      pal_ptr->red = buf[0];
      pal_ptr->green = buf[1];
      pal_ptr->blue = buf[2];
   }
#else
   for (i = 0; i < num; i++)
   {
      png_byte buf[3];

      png_crc_read(png_ptr, buf, 3);
      /* Don't depend upon png_color being any order */
      palette[i].red = buf[0];
      palette[i].green = buf[1];
      palette[i].blue = buf[2];
   }
#endif

   /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
    * whatever the normal CRC configuration tells us.  However, if we
    * have an RGB image, the PLTE can be considered ancillary, so
    * we will act as though it is.
    */
#ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
      png_crc_finish(png_ptr, (int) length - num * 3);
    }
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
   {
      /* If we don't want to use the data from an ancillary chunk,
         we have two options: an error abort, or a warning and we
         ignore the data in this chunk (which should be OK, since
         it's considered ancillary for a RGB or RGBA image). */
      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
      {
         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
         {
            png_chunk_error(png_ptr, "CRC error");
         }
         else
         {
            png_chunk_warning(png_ptr, "CRC error");
            return;
         }
      }
      /* Otherwise, we (optionally) emit a warning and use the chunk. */
      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
      {
         png_chunk_warning(png_ptr, "CRC error");
      }
   }
#endif

   png_set_PLTE(png_ptr, info_ptr, palette, num);

#ifdef PNG_READ_tRNS_SUPPORTED
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
   {
      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
      {
         if (png_ptr->num_trans > (png_uint_16)num)
         {
            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
            png_ptr->num_trans = (png_uint_16)num;
         }
         if (info_ptr->num_trans > (png_uint_16)num)
         {
            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
            info_ptr->num_trans = (png_uint_16)num;
         }
      }
   }
#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.