static Image *ReadSTEGANOImage(const ImageInfo *image_info,
  ExceptionInfo *exception)
{
#define GetBit(alpha,i) MagickMin((((size_t) (alpha) >> (size_t) \
  (i)) & 0x01),16)
#define SetBit(indexes,i,set) SetPixelIndex(indexes,((set) != 0 ? \
  (size_t) GetPixelIndex(indexes) | (one << (size_t) (i)) : (size_t) \
  GetPixelIndex(indexes) & ~(one << (size_t) (i))))

  Image
    *image,
    *watermark;

  ImageInfo
    *read_info;

  int
    c;

  MagickBooleanType
    status;

  PixelPacket
    pixel;

  register IndexPacket
    *indexes;

  register PixelPacket
    *q;

  register ssize_t
    x;

  size_t
    depth,
    one;

  ssize_t
    i,
    j,
    k,
    y;

  /*
    Initialize Image structure.
  */
  assert(image_info != (const ImageInfo *) NULL);
  assert(image_info->signature == MagickSignature);
  if (image_info->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
      image_info->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickSignature);
  one=1;
  image=AcquireImage(image_info);
  if ((image->columns == 0) || (image->rows == 0))
    ThrowReaderException(OptionError,"MustSpecifyImageSize");
  read_info=CloneImageInfo(image_info);
  SetImageInfoBlob(read_info,(void *) NULL,0);
  *read_info->magick='\0';
  watermark=ReadImage(read_info,exception);
  read_info=DestroyImageInfo(read_info);
  if (watermark == (Image *) NULL)
    return((Image *) NULL);
  watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
  if (AcquireImageColormap(image,MaxColormapSize) == MagickFalse)
    ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
  if (image_info->ping != MagickFalse)
    {
       (void) CloseBlob(image);
       return(GetFirstImageInList(image));
     }
  status=SetImageExtent(image,image->columns,image->rows);
  if (status == MagickFalse)
    {
      InheritException(exception,&image->exception);
      return(DestroyImageList(image));
    }
   /*
     Get hidden watermark from low-order bits of image.
   */
  c=0;
  i=0;
  j=0;
  i=(ssize_t) (watermark->depth-1);
  depth=watermark->depth;
  for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)
  {
    for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)
    {
      x=0;
      for ( ; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)
      {
        if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)
          break;
        (void) GetOneVirtualPixel(watermark,k % (ssize_t) watermark->columns,
          k/(ssize_t) watermark->columns,&pixel,exception);
        q=GetAuthenticPixels(image,x,y,1,1,exception);
        if (q == (PixelPacket *) NULL)
          break;
        indexes=GetAuthenticIndexQueue(image);
        switch (c)
        {
          case 0:
          {
            SetBit(indexes,i,GetBit(pixel.red,j));
            break;
          }
          case 1:
          {
            SetBit(indexes,i,GetBit(pixel.green,j));
            break;
          }
          case 2:
          {
            SetBit(indexes,i,GetBit(pixel.blue,j));
            break;
          }
        }
        if (SyncAuthenticPixels(image,exception) == MagickFalse)
          break;
        c++;
        if (c == 3)
          c=0;
        k++;
        if (k == (ssize_t) (watermark->columns*watermark->columns))
          k=0;
        if (k == image->offset)
          j++;
      }
    }
    status=SetImageProgress(image,LoadImagesTag,(MagickOffsetType) i,depth);
    if (status == MagickFalse)
      break;
  }
  watermark=DestroyImage(watermark);
  (void) SyncImage(image);
  return(GetFirstImageInList(image));
}

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.