Integer overflow: Difference between revisions

Revision as of 23:27, 1 March 2017

Revision as of 06:28, 2 March 2017

Line 93:

An unhandled arithmetic overflow in the engine steering software was the primary cause of the crash of the 1996 maiden flight of the [[Ariane 5 Flight 501|Ariane 5]] rocket.<ref>{{cite web|last=Gleick|first=James|title=A Bug and A Crash|url=http://www.around.com/ariane.html|work=New York Times Magazine|accessdate=9 December 2013|date=1 December 1996}}</ref> The software had been considered bug-free since it had been used in many previous flights, but those used smaller rockets which generated lower acceleration than Ariane 5.

On 30 April 2015, the [[Federal Aviation Authority]] announced it will order [[Boeing 787]] operators to reset its electrical system periodically, to avoid an integer overflow which could lead to loss of electrical power and [[ram air turbine]] deployment, and Boeing is going to deploy a [[software update]] in the fourth quarter.<ref>{{cite news |title= F.A.A. Orders Fix for Possible Power Loss in Boeing 787 |work= [[New York Times]] |date= 30 April 2015 |url= httphttps://www.nytimes.com/2015/05/01/business/faa-orders-fix-for-possible-power-loss-in-boeing-787.html?_r=0}}</ref> The [[European Aviation Safety Agency]] followed on 4 May 2015.<ref>{{cite web |url= http://ad.easa.europa.eu/ad/US-2015-09-07 |work= Airworthiness Directives |title= US-2015-09-07 : Electrical Power - Deactivation |date= {{date|2015-05-04}} |publisher= [[European Aviation Safety Agency]]}}</ref> The error happens after 2³¹ centiseconds ({{#expr:2^31/100/3600/24}} days), indicating a 32-bit [[Signed number representations|signed]] [[Integer (computer science)|integer]].

Overflow bugs are evident in computer games. In the arcade game ''[[Donkey Kong]]'', [[Kill screen|it is impossible to advance past level 22]] due to an integer overflow in its time/bonus. The game takes the level number a user is on, multiplies it by 10 and adds 40. When they reach level 22, the time/bonus number is 260, which is too large for its 8-bit 256 value register, so it resets itself to 0 and gives the remaining 4 as the time/bonus - too short to finish the level. In ''[[Donkey Kong Jr. Math]]'', when trying to calculate a number over 10000, it shows only the first 4 digits. Overflaw is the cause of the famous ''[[kill screen|Split Screen]]'' in Pac-Man <ref>{{cite web|url=http://home.comcast.net/~jpittman2/pacman/pacmandossier.html|title=The Pac-Man Dossier|author=Pittman, Jamey}}</ref> and the ''Nuclear Gandhi'' in [[Civilization series]].