BugTraq
Did a 16-bit counter overflow shut down Comair? Dec 28 2004 05:44PM
Richard M. Smith (rms computerbytesman com) (2 replies)
Re: Did a 16-bit counter overflow shut down Comair? Dec 29 2004 08:41AM
Avleen Vig (lists-bugtraq silverwraith com)
Re: Did a 16-bit counter overflow shut down Comair? Dec 29 2004 03:27AM
Mike Nice (niceman att net)

> Earlier this year, an overflow of a 32-bit counter in Windows shut down
air
> traffic control over southern California for 3 hours:
>
> Microsoft server crash nearly causes 800-plane pile-up
> http://www.techworld.com/opsys/news/index.cfm?NewsID=2275
>
> This problem occurred because of a known design flaw in older versions of
> Windows:
>
> http://tinyurl.com/5n9gc

Not quite true. Although an old version of Win98 had an overflow, this
overflow was in the application, not the OS.

http://www.spectrum.ieee.org/WEBONLY/resource/nov04/1104nair.html

..."But it's a software glitch that makes the reboot procedure necessary in
the first place, says Riggs. And that glitch resides in an auxiliary
system-the VSCS Control Subsystem Upgrade (VCSU)."

"Inside the control system unit is a countdown timer that ticks off time in
milliseconds. The VCSU uses the timer as a pulse to send out periodic
queries to the VSCS. "

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