This creates the ethical dilemma of passively causing multiple deaths, versus actively causing one. Leaving the switch as-is will cause it to kill multiple people (typically five) stuck on the tracks, but switching the track will cause it to kill only one person, who would not have died if the switch was left untouched. The Trolley Problem is a thought experiment where an out-of-control trolley is heading to a switch which you control. Ponytail uses the Trolley Problem, and trolley (tram) tracks in general, as an analogy for streams of instructions in a program. In the Meltdown and Spectre bugs, the results of speculatively executed instructions are not completely discarded, allowing them to affect things that the program logic should have prevented.
This allows it to keep doing useful work while some slower decision is made. Once the decision is made, it keeps results from the selected path, and discards unnecessary results. It may start speculatively executing instructions that follow a particular result of a decision before the execution of the logic that makes that decision is finished. The processor works on several successive instructions, each at a different stage in the assembly line.
#Spectre ghost malware series#
Processors handle instructions in a series of steps, like an assembly line. Speculative execution is a technique used to speed up the execution of computer programs.
The bugs result from flawed implementations of speculative execution, and made big news because they broke the "walls" between programs executing concurrently on the same computer, in some circumstances allowing malware to steal secrets from normal, bug-free programs. This comic was inspired by the Meltdown and Spectre bugs found in certain processors these vulnerabilities were disclosed to the public in the week of this comic. Title text: New zero-day vulnerability: In addition to rowhammer, it turns out lots of servers are vulnerable to regular hammers, too.
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