MagickExport Image *PingBlob(const ImageInfo *image_info,const void *blob,
  const size_t length,ExceptionInfo *exception)
{
  const MagickInfo
    *magick_info;

  Image
    *image;

  ImageInfo
    *clone_info,
    *ping_info;

  MagickBooleanType
    status;

  assert(image_info != (ImageInfo *) NULL);
  assert(image_info->signature == MagickCoreSignature);
  if (image_info->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
      image_info->filename);
  assert(exception != (ExceptionInfo *) NULL);
  if ((blob == (const void *) NULL) || (length == 0))
    {
      (void) ThrowMagickException(exception,GetMagickModule(),BlobError,
        "ZeroLengthBlobNotPermitted","`%s'",image_info->filename);
      return((Image *) NULL);
    }
  ping_info=CloneImageInfo(image_info);
  ping_info->blob=(void *) blob;
  ping_info->length=length;
  ping_info->ping=MagickTrue;
  if (*ping_info->magick == '\0')
    (void) SetImageInfo(ping_info,0,exception);
  magick_info=GetMagickInfo(ping_info->magick,exception);
  if (magick_info == (const MagickInfo *) NULL)
    {
      (void) ThrowMagickException(exception,GetMagickModule(),
        MissingDelegateError,"NoDecodeDelegateForThisImageFormat","`%s'",
        ping_info->magick);
      ping_info=DestroyImageInfo(ping_info);
      return((Image *) NULL);
    }
  if (GetMagickBlobSupport(magick_info) != MagickFalse)
    {
      char
        filename[MagickPathExtent];

      /*
        Native blob support for this image format.
      */
      (void) CopyMagickString(filename,ping_info->filename,MagickPathExtent);
      (void) FormatLocaleString(ping_info->filename,MaxTextExtent,"%s:%s",
        ping_info->magick,filename);
      image=ReadStream(ping_info,&PingStream,exception);
      if (image != (Image *) NULL)
        (void) DetachBlob(image->blob);
      ping_info=DestroyImageInfo(ping_info);
      return(image);
    }
  /*
    Write blob to a temporary file on disk.
  */
  ping_info->blob=(void *) NULL;
  ping_info->length=0;
  *ping_info->filename='\0';
  status=BlobToFile(ping_info->filename,blob,length,exception);
  if (status == MagickFalse)
    {
      (void) RelinquishUniqueFileResource(ping_info->filename);
      ping_info=DestroyImageInfo(ping_info);
      return((Image *) NULL);
    }
  clone_info=CloneImageInfo(ping_info);
  (void) FormatLocaleString(clone_info->filename,MaxTextExtent,"%s:%s",
    ping_info->magick,ping_info->filename);
  image=ReadStream(clone_info,&PingStream,exception);
  if (image != (Image *) NULL)
    {
      Image
        *images;

      /*
        Restore original filenames and image format.
      */
      for (images=GetFirstImageInList(image); images != (Image *) NULL; )
      {
        (void) CopyMagickString(images->filename,image_info->filename,
          MaxTextExtent);
        (void) CopyMagickString(images->magick_filename,image_info->filename,
          MaxTextExtent);
        (void) CopyMagickString(images->magick,magick_info->name,MaxTextExtent);
        images=GetNextImageInList(images);
      }
    }
  clone_info=DestroyImageInfo(clone_info);
  (void) RelinquishUniqueFileResource(ping_info->filename);
  ping_info=DestroyImageInfo(ping_info);
  return(image);
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.