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History's Worst Software Bugs
bharatm writes "Wired has an article on the 10 worst sofware bugs.. From the article 'Coding errors have sparked explosions, crippled interplanetary probes -- even killed people. Here's our pick for the 10 worst bugs ever, but the judging wasn't easy.'"
I wouldnt say they are the 10 worst bugs ever... more like the 10 most widely known media announced bugs. Okay I have no examples of any others but I'm sure there must be worse bugs out there...
anyone think of any others?
why?
1995/1996 -- The Ping of Death. A lack of sanity checks and error handling in the IP fragmentation reassembly code makes it possible to crash a wide variety of operating systems by sending a malformed "ping" packet from anywhere on the internet. Most obviously affected are computers running Windows, which lock up and display the so-called "blue screen of death" when they receive these packets. But the attack also affects many Macintosh and Unix systems as well.
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WinNuke made it...
MoM++ - A Classic Expanded - [Master of Magic 1.5]
http://mompp.sourceforge.net/
The last one on the list is this
... to me that sounds like a user not using the software correctly..
"Multidata's software allows a radiation therapist to draw on a computer screen the placement of metal shields called "blocks" designed to protect healthy tissue from the radiation. But the software will only allow technicians to use four shielding blocks, and the Panamanian doctors wish to use five.
The doctors discover that they can trick the software by drawing all five blocks as a single large block with a hole in the middle. What the doctors don't realize is that the Multidata software gives different answers in this configuration depending on how the hole is drawn: draw it in one direction and the correct dose is calculated, draw in another direction and the software recommends twice the necessary exposure.
At least eight patients die, while another 20 receive overdoses likely to cause significant health problems. The physicians, who were legally required to double-check the computer's calculations by hand, are indicted for murder. "
why?
Wonderful article. Twenty years ago I believed that writing software would soon become a licensed profession. (Need alicense to own a compiler, for instance.) I thought that the event that would inevitably trigger this is when a software bug caused a human death.
This is like saying you need a license to operate a Soda Vending Machine because some idiot decided tipping it over trying to get a free soda was a smart idea. You might have to put warnings on compliers like do not code if you have no clue what you are doing, etc but requiring a license won't ever happen. I am sure there will be lawsuits in the future regarding software bugs, but any software being used where an error could cause a human death is going to have a corporation behind it, that can be held responsible.
I've read about this instance before, and I think it's attributable to ignorance on both the user and the developer. The software developer in this case knows the life of a human being is resting on his code, so it should have been nigh impossible to "trick" the software into allowing anything other than what the specs said it could do.
Proud member of the American Non Sequitur Society. We might not make much sense, but boy do we love pizza!
What a fool believes, he sees, no wise man has the power to reason away.
That is wrong. This is a myth that has been disproved several times. See for example the "IEEE Annals of Computer History" where Adm. Grace Hopper said that that the term "bug" was used at least since the 30s, and maybe earlier, to describe an electrical problem in a system. See also here.
In interview, Hopper confirmed that the notebook moth's caption, "First actual case of bug being found", clearly shows that it was a joke referring to a term that was already in use at the time.
Any idiot researching this anecdote for five minutes could have found about it. I guess Wired couldn't be bothered. At this level of laziness and incompetence, one wonders why they just don't start publishing printouts of slashdot laced with ads. At least, this place contains occasional nudgets of truth.
Once again, Wired blew it. Nice jobs, guys.
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For potential severity, this one's worse than a few they listed.
Basically, the Navy was running critical ship systems on a Windows NT platform, and a divide-by-zero in a database caused a buffer overrun that resulted in a shutdown of the engines, leaving the ship dead in the water for 2.5 hours.
Fortunately, it was on maneuvers off of Cape Charles, and not at war off the coast of Yemen or something. Scratch a billion-dollar destroyer and most of her crew because of an NT bug, in that case.
Why isn't Outlook Express in here? Early versions basically changed unopened e-mail viruses from a hoax to reality, when Microsoft decided it was a *good* idea to automatically run any VB script that was recieved. That's cluelessness like trusting everyone to be good and decent human beings while you walk through a prison shower with "Please rape me" painted on your back.
Later versions tried to fix the problem while keeping the functionality, as if somehow the bad guys would intentionally include the Evil Bit in their code.
"No problem. I have the capacity to do infinite work so long as you don't mind that my quality approaches zero."-Dilbert
However, you have been fooled. The parent comment is competely at odds with the article.
The article shows largely a series of examples where you DID have HIGHLY PAID and HIGHLY trained professionals with plenty of experience and oversight, but nevertheless very significant bugs occurred. So, the real lesson from this article is not "you get what you pay for," but rather that "software development is very hard" and perhaps that "by nature of its hardness, we can expect critical flaws to pop up from time to time, even when highly trained, experienced, and monitored programmers are involved."
It's not a software bug, it's a user error.
It's both. The program should not have accepted easily recognised invalid input and the user should not have entered it.
I don't care if it's not in the spec, it's commonly accepted programming practice that all input should be bounds checked and any program that doesn't do that is crap.
Your rm example is not equivalent as command line programs are by design flexible; in unusual circumstances it may be exactly what the operator wants to do.
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Keep your options open!
Some of the bugs reported in the story were not so much the fault of programmers, but of management. The phone network bug was a misplaced { character in a nested if-else construct. The code had already been though extensive testing, and then a small change was needed. Because it was a "minor" change someone said it didn't need to go through the extensive (expensive) testing again. It's always easy to point at the code or the guy who wrote it. Especially when the boss is the one tasked with finding out what went wrong.
It doesn't matter how highly paid and trained your professionals are, if the environment that produces the software is not conducive to eliminating these types of flaws. Like if they are not given enough resources to test and QA the the projects they are assigned, there is no organizational commitment to take the time and expense to document properly, or leadership overrides technical objections to project timeframes, etc. Most of the cited projects could probably be classified as failures of project management rather than failures of the end product (the software) that these flawed projects produced. Yes, software is hard and the software profession should continue its efforts to improve quality, but that doesn't let the organizational culture, leadership and processes that produced the software in these cases off the hook.
Why is it when the accounting profession makes spectacular mistakes that take down entire Fortune 500 class organizations, there is a critical analysis of the processes that led to these failures, and remedies often comprise prescriptive measures for these processes, but similar analysis for software failures focus upon the software flaw but not the environment that allowed the flaw to emerge? Now sometimes the remedy in the accounting case might not make complete sense (like SOX), but the point here is people don't look at just the end result (the accounting system transactions) of the accounting process.
Look, I write software for control systems (and I design them electrically too). Just because programmers at Microsoft or EA Games have tight schedules where they are just too stressed to write code well doesn't mean all code needs to be written like that.
Back to what you were saying, if you have a system that could cause damage or whatever, then you start by writing your output routines, and you create rules to govern the machine (i.e. outputs A and B can't come on at the same time, or output C can't exceed this value). Then you write another module that monitors the inputs AND outputs looking for fault conditions that shuts down the machine if you do anything dangerous. Only this part of the code needs to be signed off by an engineer. Typically it's simple code, and easy to prove correct, with peer review. Then you write other modules that essentially make requests through the safety checks to do anything. You don't have to review the complex other code so much, because your output stage should catch any mistakes.
That's how you make a machine safe. Unfortunately, most engineers I know just go out and write the software figuring there's no difference, and that's how bad things happen. It comes from believing you won't make a mistake, or believing that testing will catch all problems. If you plan from the start that you're going to be making mistakes, you can catch them before damage is done. It's too bad this isn't taught, even in the software engineering classes I took at a Canadian university.
"I have never let my schooling interfere with my education." - Mark Twain
1. Design reviews, by peers and independents
2. Code reviews, by peers and independents
3. Regulary, organized, unit testing
4. Correctness proving
5. Documentation is about a bazillion forms
6. Defect tracking
7. Effective software process metrics measurement and improvement
8. Continuing education
9. Humility / egoless programming
This list was assembled in about a minute off the top of my head. I work in a CMM3/4 type organization, and although there are processes for these things, most people don't use them, or consider them a hassle.
So my point is, the parent is right -- creating good software, even when done by properly trained experts with great experience -- is hard. But the grandparent is right too -- doing all of the above to 'do it right' takes time and money, and many organizations, and by this I mean software process management as well as the actual engineers, don't understand the value / aren't willing to pay for or aren't willing to do all that work. And occasionally, as the article shows, the piper comes and takes his payment.
In Soviet Russia, us are belong to all your base.
It really doesn't matter what language you use: bugs can be written in any of them. In this case, the customer wanted a GUI workstation running on Windows, with the possibility of being cross-platform. Java was new and cool (1.1 had been out for six week when we started), and they decided to give it a shot. This is a company with fifty years experience in medical systems, not some dotcom startup, so the procedures are in place to make sure that their products don't kill people.
As it turns out, JDK1.1 (along with a native-C library for quick image processing, and a custom PCI card for doing 30MB/sec image transfers) was just fine for the task. We had a team of seven testers working on the project full time for a year, and were able to ship with zero severity 1-2 defects.
We set a new record for lowest defects/KLOC at the customer (a major player in the medical systems industry), despite running JDK 1.1 on Windows NT 4. Our product was several times faster than the C-based product it replaced, had more functionality, and provided more accurate diagnosis for the patient.
Good design is the most important thing in developing good software. The language/runtime/OS can provide crutches to save you if you screw up, but bad design will result in defects no matter how sturdy the crutches are.
"If Engineers built buildings the way computer programmers wrote programs, the first woodpecker that came along would destroy civilization."
If engineers built buildings the way computer programmers wrote programs, an average engineer would be able to build an array of radio telescopes by himself in one evening. A team of 30 engineers would be able to build a ringworld in 3 months.
i.e. it would be nice if software were like designing an office, where there were 3 architects, 5 engineers, a building inspector, and 50 professional workmen to examine a system containing just a few hundred variables, and almost identical to the last 20 buildings they'd constructed.
And in case that didn't start a flamewar, how about...
"Just one unexpected input (of an aeroplane) caused the failure of two of New York's biggest civil engineering projects -- imagine how they'd cope with being attacked every 3 seconds like some internet software"