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To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
CC: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
Subject: RE: [EXTERNAL] Re: Fork bomb question about Cygwin
Thread-Topic: [EXTERNAL] Re: Fork bomb question about Cygwin
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From: "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\] via Cygwin" <cygwin AT cygwin DOT com>
Reply-To: "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\]" <lavr AT ncbi DOT nlm DOT nih DOT gov>
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Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

> Yes.  As on Linux and other systems, there's no default restriction(*)
> for the number of processes of an unprivileged user.

> This is not something controlled by Cygwin, rather by the OS.  Cygwin
> provides the POSIX calls getrlimit/setrlimit, but obviously those have
> to be implemented in terms of OS functions or faked.
> 
> The only implemented limits are RLIMIT_AS, RLIMIT_CORE, RLIMIT_NOFILE
> and RLIMIT_STACK, and only RLIMIT_AS is actually calling into the OS to
> install a restriction.

Thank you, Corinna, for all the explanations!

So basically, Windows is inherently susceptible for the fork bomb attack, and there's nothing Cygwin-specific in this vulnerability, or something that Cygwin can add to make it worse than it already is.

Anton Lavrentiev
Contractor NIH/NLM/NCBI

P.S. As a "regular" Linux user, I do have the process limit in my environment set as 2048, and I think that's effectively protects the system from the runaway situation.  Also, it looks like I have never hit this limit in the real use-case scenarios so it is quite adequate not to interfere with the day-to-day work.

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