A colleague challenged me, half jokingly, to perform a code review of the Linux kernel. I took his challenge: I downloaded the latest stable kernel sources and used a state of the art static code checker (grep -hEir “hack|crack|backdoor|keygen” *).
I located a couple of backdoors:
Some cracks:
And even some keygens:
And the number of hacks was countless (1000+), here is a selection:
Didier Stevens 
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