Re: Fwd: Simple kernel attack using socketpair. easy, 100% reproductiblle, works under guest. no way to protect :(

[Eric Dumazet <eric.dumazet@gmail.com>]

Le jeudi 25 novembre 2010 à 12:52 +0500, Марк Коренберг a écrit :
> ---------- Forwarded message ----------
> From: Марк Коренберг <socketpair@gmail.com>
> Date: 2010/11/25
> Subject: Re: Simple kernel attack using socketpair. easy, 100%
> reproductiblle, works under guest. no way to protect :(
> To: Eric Dumazet <eric.dumazet@gmail.com>
> 
> 
> 2010/11/25 Eric Dumazet <eric.dumazet@gmail.com>:
> > Le jeudi 25 novembre 2010 à 11:52 +0500, Марк Коренберг a écrit :
> >> Well, It seems, that patch likely will fix 100% CPU usage.
> >>
> >> But what about eating all available descriptors in kernel ? vulnerability ?
> >>
> >
> > It doesnt fix cpu usage actually, your program eats 100% of one cpu,
> > like the following one :
> >
> > for (;;) ;
> >
> > If you want not eat 100% cpu, I suggest you add some blocking calls,
> > like usleep(10000)
> >
> > for (;;) usleep(10000);
> >
> > Patch only makes sure kernel wont eat too much memory to store inflight
> > unix sockets.
> 
> I have attached source which proove, that loop not inside this
> program, but inside kernel.
> 
> --

Better send a fix, now that thousand of people know how to kill a linux
machine.

Congrats.