From: NetSurfer <jdwilson@gold.chem.hawaii.edu>
Date: Wed, 14 Dec 94 09:54:14 PST
To: cypherpunks@toad.com
Subject: Re the Pentium Bug
Message-ID: <199412141759.MAA19955@bb.hks.net>
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  NASIRC BULLETIN #94-36                                    December 13, 1994

          Floating Point Divide Flaw in Intel Pentium Processor Chip
         ============================================================
               __    __      __      ___   ___  ____     ____  
              /_/\  /_/|    /_/     / _/\ /_/| / __/ \  / __/\ 
              | |\ \| ||   /  \ \   | /\/ | || | /\ \/  | | \/ 
              | ||\ \ ||  / /\ \ \   \ \  | || |_\/ /\  | |    
              | || \ \|| / /--\ \ \ /\_\\ | || | |\ \ \ | \_/\ 
              |_|/  \_|//_/    \_\/ \/__/ |_|/ |_| \_\/ \___\/ 
             NASA Automated Systems Incident Response Capability
         ============================================================

  NASIRC  has  become  aware of  a floating-point  division problem in  some
  versions  of the Pentium  processor chip,  manufactured by Intel. Although
  this is not a security  issue,  NASIRC  is bringing this to your attention
  because  the  defect could cause erroneous results for NASA projects which
  rely  on  complex   mathematical computations  involving  double-precision
  arithmetic.

  Information on this problem  is  currently  being  propagated  through the
  Internet and both technical and general publications.  We are issuing this
  bulletin to provide a synopsis of what is known about the problem,  how to 
  check for the flaw, and what to do about it. 

  It is important  that  any  individual  who  uses  a  computer utilizing a
  Pentium  processor  perform  the  test(s)  described  in  this bulletin on
  his/her  machine  to  check for the bug.  Although there have been reports
  the  Pentium/60  is not  affected,  NASIRC  recommends these units also be
  tested. 

  There  is no part number or other marking which would designate the flawed 
  processor chips from the later revisions, which do not contain the bug.

  Intel  considers  this  flaw  to  be minor,  and has  stated: "the average
  spreadsheet  user  should  only  be affected by this bug once every 27,000
  years".  However,  NASIRC feels there is a high probability that work done
  on  this  class  of   desktop  system  in  NASA   is  most  likely  to  be
  computationally intensive,  and  the  likelihood  of  achieving  erroneous
  results is strong. From a reliability and reputation standpoint, NASA must
  ensure  that the tools it uses to accomplish its mission perform properly.
  The  president  of  Intel  has  issued a communique, stating his company's
  position  on  the  problem,   and  the the process to follow should a site 
  discover  a  flawed system.  The  communique  is  available via WWW at the
  URL:  http://www.intel.com/about-intel/press/andy-msg.html. 

  Pentium machines can be tested by using any of the following three 
  methods: 


1) Using the Microsoft Windows calculator, perform the following
   computation: 

     x = 4195835
     y = 3145727
     z = x - (x/y)*y

   If z = 256, your chip has the bug.  The Windows calculator is the
   easiest way to run this test. If you program this calculation, be
   sure to use to use double-precision variables!


2) Using any spreadsheet application (Lotus 1-2-3, Excel, etc), perform
   the following test:

     Enter the following data:

     In cell A1:    4195835
     In cell A2:    3145727
     In cell A3:    3145727

     Calculate the following value:

               (A1 * A2)/A3

     A correct result is: 4195835

     An incorrect result (FDIV bug) is: 4195579



3)   A small program named P87TEST.COM, to test for the existence of the 
     bug  was  written  and  made  available  over the Internet by Terje 
     Mathisen of Norsk Hydro A/S in Norway.

     A binary copy of P87TEST.COM can be obtained via anonymous FTP from
     the NASIRC online archive at the following URL: 

	ftp://nasirc.nasa.gov/toolkits/diagnostics/Intel/p87test.com

     The Checksums are as follows:

       MD5: 322E8857C126D7CA336E7FFC31800939
       SunOS: 08334     2

     To run the program, simply type: P87TEST. An example of the 
     program output is as follows:

	Pentium FDIV bug finder. (c) Terje Mathisen 1994
	
	This is a Pentium or better cpu

	CPUID reports back:
	Vendor id = "GenuineIntel"
	Family (4=486, 5=Pentium etc.) = 05, stepping = 05, model = 01
	CPU feature list:
	  1 : FPU (NDP) onchip
	  2 : Virtual 86 Mode Extensions
	  4 : I/O Breakpoints
	  8 : Page Size Extensions
	 10 : Time Stamp Counter
	 20 : Pentium stype MSRs
	 80 : Machine Check Exception
	100 : CMPXCHG8B instruction available
	It has a 387 or later ndp
	It has the FDIV bug:
	(1.0/824633702449.0)*824633702449.0 is not equal to 1.0!



  Intel  has  stated  that any site experiencing problems from this bug 
  can obtain a replacement processor chip at no charge.

  Intel  has  set  up a special customer service phone number for users
  affected  by  this  bug.  The  Intel customer service desk can assist
  with  obtaining  replacement  processor  chips  for affected systems.

  Any site confirming the existence of the bug in their Pentium chipset 
  should contact Intel at 1-800-628-8686.

  If  you  have  any questions  about this bulletin, please contact the 
  NASIRC Helpdesk.

     =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
     NASIRC ACKNOWLEDGES:  Mr. Bob Solomon  of  the NASA Lewis Research 
       Center for  providing  the  information  used  in this bulletin,
       and Mr. Terje Mathisen of Norsk Hydro A/S for creating the pro- 
       gram to test a system for the bug.
     =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

       ===============================================================
         For further assistance, please contact the NASIRC Helpdesk:
            Phone: 1-800-7-NASIRC             Fax: 1-301-441-1853
                       Internet Email: nasirc@nasa.gov
             24 Hour/Emergency Pager: 1-800-759-7243/Pin:2023056
                           STU III: 1-301-982-5480
       ===============================================================
       This bulletin may be forwarded without restriction to sites and 
              system administrators within the NASA community.
 
       The NASIRC online archive system is available via anonymous ftp.
       You will be required to enter  your valid e-mail address as the
       "password".   Once on the system,  you can access the following
       information:

           ~/bulletins          ! contains NASIRC bulletins
           ~/information        ! contains various informational files
           ~/toolkits           ! contains automated toolkit software
        
       The contents  of these  directories is  updated on  a continuous
       basis with relevant software and information; contact the NASIRC 
       Helpdesk for more information or assistance.
 
                              -----------------
 
     PLEASE NOTE: Users outside of the NASA community  may receive NASIRC
     bulletins. If you are not part of the NASA community, please contact
     your agency's response team to report incidents.  Your agency's team
     will coordinate  with NASIRC,  who will  ensure the  proper internal
     NASA team(s)  are notified.   NASIRC is  a member  of  the  Forum of
     Incident Response and Security Teams (FIRST), a world-wide organiza-
     tion which provides for coordination between incident response teams
     in handling computer-security-related issues.  You can obtain a list
     of FIRST  member organizations  and their  constituencies by sending
     email to   docserver@first.org   with an empty  "subject" line and a
     message body containing the line "send first-contacts".



*************************************************************************
* Richard K. Yamane			      Leeward Community College	*
* Manager, Computer Center		      96-045 Ala Ike		*
*                                             Pearl City, Hawaii 96782	*
* EM: sysrich@lccada.lcc.hawaii.edu					*
* Ph: (808) 455-0493			      (Univ. of Hawaii campus)	*
*************************************************************************

**************************************************************************
*Marv Weissman  *  UH Computer Specialist  *  Leeward Community College  *
*cs_weissman@lccada.lcc.hawaii.edu  (808)455-0465, voice.  455-0471, fax *
*                                                                        *
* "Don't worry about what may happen tomorrow; just correct what you     *
*    spoiled yesterday"                                                  *
*                                                                        *
*			(Midrash    )                                    *
*                                                                        *
*************************************************************************      





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