Thursday, May 7, 2009

Blog Wars : Episode V : History’s Top Ten Software Bugs

BlogWars EP 5

Let's See the History's Top Ten Software Bugs and its consequences

10 : Mars Climate Orbiter Crashes - 1998

Bug : The Sub contractor Used Imperial Units for calculation instead of Metrics as specified by NASA

Result : The $125 million dollar space craft attempted to stabilize its orbit too low in the Martian atmosphere, and crashed into the red planet.

9: Mariner I space probe - 1962

Bug : The formula was written in a paper (mission critial formula) using pencil and the programmer missed the superscriptbar and that's it everything is gone, (happened in NASA)

 Result : The probe was set to travel to Venus but had 237 seconds of flight and the path devated and the Earth Probe crew destroyed in Atlantic Ocean

8: Ariane 5 Flight 501 - 1996

Bug : This time it's European Space Agency, they just took the code from Ariane 4 (predecessor) and re used it. But the New version tried to covert engine velocity which is a 64 bit number into 16 bit space and resulted in Stack Overflow exception both Primary and Backup Computer failed . I guess there is no try catch was used:)

Result : Barely 36.7 seconds into its maiden launch, the self destruct safety mechanism was activated due to the computer failures, and the spacecraft disintegrated in a spectacular fireball. The Ariane 5 had cost nearly $8 billion to develop, and was carrying a $500 million satellite payload when it exploded.

7: EDS Fails Child Support - 2004

Bug : EDS software giant introduced a large, complex IT system to the U.K.’s Child Support Agency (CSA). At the exact same time, the Department for Work and Pensions (DWP) decided to restructure the entire agency. The restructure and the new software were completely incompatible, and irreversible errors were introduced as a result

Result : The system somehow managed to overpay 1.9 million people, underpay another 700,000, had $7 billion in uncollected child support payments, a backlog of 239,000 cases, 36,000 new cases “stuck” in the system, and has cost the UK taxpayers over $1 billion to date.

6: Soviet Gas Pipeline Explosion - 1982

Bug : Operatives working for the Central Intelligence Agency(CIA) (allegedly) plant a bug in a Canadian computer system purchased to control the trans-Siberian gas pipeline. The Soviets had obtained the system as part of a wide-ranging effort to covertly purchase or steal sensitive U.S. technology. The CIA reportedly found out about the program and decided to make it backfire with equipment that would pass Soviet inspection and then fail once in operation.

 Result : The resulting event is reportedly the largest non-nuclear explosion in the planet's history.

5: AT&T Network Outage - 1990

Bug : A bug in a new release of the software that controls AT&T's #4ESS long distance switches causes these mammoth computers to crash when they receive a specific message from one of their neighboring machines -- a message that the neighbors send out when they recover from a crash

Result :114 switches are crashing and rebooting every six seconds, leaving an estimated 60 thousand people without long distance service for nine hours. The fix was they reloaded the previous version of software

4: Intel Pentium floating point divide - 1993

Bug :A slight error causes Intel's highly promoted Pentium chip to make mistakes when dividing floating-point numbers that occur within a specific range. For example, dividing 4195835.0/3145727.0 yields 1.33374 instead of 1.33382, an error of 0.006 percent. However its small it became a nightmare in the Intel's Public relationship management

Result : Eventually the company relents and agrees to replace the chips for anyone who complains. The bug ultimately costs Intel $475 million.

3: Multidata Systems - 2000

Bug : A U.S. firm, Multidata Systems International, created therapy planning software that was designed to calculate the proper dosage of radiation for patients undergoing radiation therapy. The software allows a radiation specialist to draw on their screen where they would be placing metal shields (called “blocks") on the patient during treatment. These blocks protect healthy tissue from the radiation. The software itself only allows the placement of 4 blocks, but the Panamanian doctors normally used five. To get past the limitation in the software, the doctors decided to trick the software by drawing all five blocks as a single block with a hole in the middle. Unfortunately, a bug in the Multidata software caused it to give different results depending on how the hole was drawn. Draw it one way and the dosage was correct. Draw it in the other direction and the software recommended twice the correct dosage.

Result : 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

2: Patriot Missile Bug - 1991

Bug : During the first Gulf War, an American Patriot Missile system was deployed to protect US Troops, allies, and Saudi and Israeli civilians from Iraqi SCUD missile attacks. A software rounding error in the one of the early versions of the system incorrectly calculated the time, causing it to ignore some of the incoming targets

 Result : A Patriot Missile Battery in Saudi Arabia fails to intercept an incoming Iraqi SCUD. The missile destroyed an American Army barracks, killing 28 soldiers and injuring around 100 other people And the #1 spot goes for . . .

1: World War III… Almost - 1983

Bug : In 1983, Soviet early warning satellites picked up sunlight reflections off cloud-tops and mistakenly interpreted them as missile launches in the United States. Software was in place to filter out false missile detections of this very nature, but a bug in the software let the alerts through anyway. The Russian system instantly sent priority messages up saying that the United States had launched five ballistic missiles. Protocol in such an event was to respond decisively, launching the entire soviet nuclear arsenal before any US missile detonations could disable their response capability. The duty officer for the system, one Lt Col Stanislav Petrov, intercepted the messages and flagged them as faulty, stopping the near-apocalypse. He claimed that he had a “funny feeling in my gut” about the attack, and reasoned if the U.S. was really attacking they would launch more than five missiles.

Result : Lucky nothing happened due to gut feelings of the Lt. but the world was literally minutes away from “Global Thermal Nuclear War”. Any retaliatory missile launched by the Soviets would have triggered a like response from the U.S., eventually leading to a total launch of all systems from both sides

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