Re: [SystemSafety] Stupid Software Errors [was: Overflow......]

From: Derek M Jones < >
Date: Mon, 04 May 2015 17:28:23 +0100


Daniel,

You webpage lists some interesting looking publications. I wish you supplied links to downloadable pdfs.

> some performance figures about an Astrée analysis for a Level A avionics
> application:
> - code size > 700.000 lines of C code
> - analysis duration: 6 hours
> - hardware: Intel Core2Duo 2.66 GHz, 8GB RAM.

A very large program analysed in not a lot of time for what is claimed. Of course the devil is in the details.

> - result: 0 alarms
> I.e. the absence of run-time errors was proven, including arithmetic
> overflows.

Lots of companies provide provide guarantees (well, perhaps not software companies), do you?
If a run-time error is found and fixed do you guarantee to provide some form of refund or to rerun your checking service on the updated code for free?

If you do provide a guarantee could you post a link to the small print, i.e., what is the definition of run-time error and under what conditions is the proof guaranteed to apply.

>
> Best regards,
> Daniel.
> ---
> Dr.-Ing. Daniel Kaestner ----------------------------------------------
> AbsInt Angewandte Informatik GmbH Email: kaestner_at_xxxxxx > Science Park 1 Tel: +49-681-3836028
> 66123 Saarbruecken Fax: +49-681-3836020
> GERMANY WWW: http://www.AbsInt.com
> ----------------------------------------------------------------------
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>
>
>> -----Ursprüngliche Nachricht-----
>> Von: systemsafety-bounces_at_xxxxxx > [mailto:systemsafety-bounces_at_xxxxxx >> von Derek M Jones
>> Gesendet: Montag, 4. Mai 2015 15:42
>> An: systemsafety_at_xxxxxx >> Betreff: Re: [SystemSafety] Stupid Software Errors [was: Overflow......]
>>
>> Peter,
>>
>>> I don't buy Derek Jones's or Tom Ferrell's versions of the curate's
> egg. I don't see why anyone
>>> else should, either. Are they still going to be saying "well, it
> depends, it's complicated" in
>>
>> Blustering in the face of reality is unbecoming.
>>
>> Very thorough static analysis requires:
>>
>> o lots of memory. I have written about how optimizing compilers
> took
>> off in the 1990s because developers finally had computers containing
>> enough memory for high level optimization techniques to be used:
>>
> http://shape-of-code.coding-guidelines.com/2011/10/08/memory-capacity-and-
> commercial-compiler-development/
>> Static analysis requires even more memory. Cloud providers now offer
>> machines containing a quarter of a terrabyte of main memory; that
>> should be enough.
>>
>> o lots of cpu power. Again the cloud now provides this, but some
>> work is needed to figure out how to parallelize what to data are
>> single threaded solutions.
>>
>> o willingness to put up with lots of false positives. These
>> customers are easy to spot because the Unicorns they rid to work on
>> are corralled in the car park.
>>
>> o the commercial incentive to make it happen. My experience is
>> that most developers are more interested being able to change the
>> colours on the user interface that what static analysis tools do.
>> Which is why after initial development most commercial static
>> analysis R&D goes on the IDE.
>>
>> So we are now in the position that the computational resource
>> problem is solved. I don't think the last two problems will be
>> solved until we start sending developers and their managers to
>> prison for delivering code containing faults that could have been
>> detected.
>>
>>
>>> another twenty years when stupid coding errors still make it through
> into supposedly-dependable
>>> software products?
>>>
>>> Look at go-to fail. That's critical code! How come critical code such
> as that is not routinely
>>> subject to static analysis?
>>>
>>> Look at the 787 generator code. A systematic loss of all generators is
> surely a hazardous event.
>>> That should make it 10^(-7). Oh, but I forgot. Even though correct
> operation of SW contributes to
>>> the 10^(-7), the reliability of the SW itself is not assessed. But
> surely it gets to be at least
>>> DAL B, since the result is a hazardous event? Oh, but I forgot
> something else. A systematic
>>> failure like that would be common cause, and the certification
> requirements concern single
>>> failures, not common cause failures. So that's all right then. Tom's
> suggestion that it might have
>>> been a design compromise is vitiated by the fact that the phenomenon
> is subject to an
>>> AIRWORTHINESS Directive by the FAA. (Is that sufficient emphasis?)
>>>
>>> If people had told me thirty years ago that we'd still be making the
> same stupid mistakes in the
>>> same ways, but this time in code more fundamental to the safe or
> secure operation of everyday
>>> engineered objects, I wouldn't have believed it.
>>>
>>> Maybe it's a social thing. Mostly, people actually writing the code
> and inspecting it are in their
>>> twenties and their bosses maybe at most in their early thirties. The
> young people have never made
>>> *this* mistake before - the previous lot had of course, but they're
> all in management now. I'm
>>> reminded of Philip Larkin's ode to rediscovery, Annus Mirabilis:
>>>
>>> Sexual intercourse began
>>> In nineteen sixty-three
>>> (Which was rather late for me)-
>>> Between the end of the Chatterley ban
>>> And the Beatles' first LP.
>>>
>>> The Ensuing Discussion.
>>>
>>> There was obviously discussion on the list of why we are making the
> same old mistakes forty years
>>> after it was known how to avoid them. Some discussants suggested it
> might help to professionally
>>> certify software engineers, a PE. Others referred to the
> Knight-Leveson study a decade ago for the
>>> ACM, in which inserting SE into the current PE scheme was not seen as
> advantageous. UK discussants
>>> pointed out that such certification exists in the UK, as a CEng
> through the BCS or IET, and that
>>> there had been some UK consideration of extra qualification for
> critical-software engineering.
>>>
>>> Such qualification for system safety hasn't (yet) generally caught on
> anywhere. SARS offer it in
>>> the UK for example. It didn't catch on in the US. Over a decade ago,
> the System Safety Society
>>> introduced an option for system safety engineering into the PE exam.
> They had to pay the NPSE or
>>> NCEES (I forget which) lots of money per year to maintain the option -
> and two people took it in
>>> some number of years. So they dropped it. (I was at the board meeting
> in Ottawa in 2004 when this
>>> was decided.)
>>>
>>> The UK qualification regime hasn't stopped IT disasters in government
> procurement. And it hasn't
>>> stopped the kind of poor engineering which allows bank ATMs which use
> supposedly
>>> pseudo-one-time-pad nonce generation to be subject to replay attacks
> (see a recent paper reciting
>>> local experiments performed by Ross Anderson's group). I do note,
> however, that the three examples
>>> I mentioned above are all US examples. It's not ruled out that having
> some degree of formal
>>> professional training, as in the UK, encourages software engineers to
> avoid repeating simple
>>> mistakes whose prophylaxis has been well known for decades.
>>>
>>> Time was, when UK and US cars were not known for their reliability.
> Kind of like SW,
>>> relatively-inexpensive cars used to go wrong a lot. However, some very
> expensive cars such as made
>>> by Rolls-Royce/Bentley and Wolseley were reliable. So there was proof
> of concept. Japanese
>>> companies decided it was possible to produce reliable
> relatively-inexpensive cars and make money,
>>> and did it.
>>>
>>> There is proof of concept in SE, too. Unlike Rolls-Royce cars, it is
> not prohibitively expensive.
>>> Three out of my four examples involve run-time error. It is feasible
> to produce SW
>>> cost-effectively which is free from run-time error. Just like the
> Japanese approach to cars, you
>>> just have to decide to do it.
>>>
>>> How about the following? We design a document called A Programmer's
> Pledge. It has thirty or so
>>> numbered clauses:
>>>
>>> * I promise never to deliver SW which is subject to a data-range
> roll-over phenomenon (especially
>>> dates and times)
>>>
>>> * I promise never to deliver software which is subject to a numerical
> overflow or underflow exception
>>>
>>> * I promise never to deliver software which reads data on which it
> raises an "out of range" exception
>>>
>>> * ..... and so on
>>>
>>> A professional programmer signs it and files it with hisher
> professional organisation. Quality
>>> control issues in programs (such as the above phenomena) are routinely
> subject to RCA of sorts.
>>> When a programmer is responsible for a piece of code with such an
> error in it, the company reports
>>> it to the professional organisation and the programmer gets "points"
> attached to the corresponding
>>> clause in hisher Pledge. Like with driving (Germans say "points in
> Flensburg" which is where the
>>> office is. What is it in the UK? "Points in Cardiff"?). I bet lots of
> organisations, from
>>> companies hiring programmers to professional-insurance companies will
> find uses for it.
>>>
>>> PBL
>>>
>>> Prof. Peter Bernard Ladkin, Faculty of Technology, University of
> Bielefeld, 33594 Bielefeld, Germany
>>> Je suis Charlie
>>> Tel+msg +49 (0)521 880 7319 www.rvs.uni-bielefeld.de
>>>
>>>
>>>
>>>
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>>> _______________________________________________
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>>
>> --
>> Derek M. Jones Software analysis
>> tel: +44 (0)1252 520667 blog:shape-of-code.coding-guidelines.com
>> _______________________________________________
>> The System Safety Mailing List
>> systemsafety_at_xxxxxx > .
>

-- 
Derek M. Jones           Software analysis
tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com
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Received on Mon May 04 2015 - 18:29:00 CEST

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