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Re: client-side memory buffers


From: Neal H. Walfield
Subject: Re: client-side memory buffers
Date: Tue, 01 Apr 2008 17:51:16 +0200
User-agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (Shij┼Ź) APEL/10.6 Emacs/21.4 (i486-pc-linux-gnu) MULE/5.0 (SAKAKI)

At Tue, 1 Apr 2008 08:11:30 -0600,
Joshua Stratton wrote:
> On Tue, Apr 1, 2008 at 2:28 AM, Neal H. Walfield <neal@walfield.org> wrote:
> > The problem is exactly the same as that with L4's data spaces.  When
> > the server maps and accesses the memory object, the client can revoke
> > the mapping at any time (via memory_object_lock_request), causing the
> > server to fault.  If you manage to unmap the memory while the server
> > is blocked on it (waiting for it to be paged in) and has a lock,
> > you've successfully created a denial of service.
> 
> 
> Okay, so it's a bad idea, for example, to juggle ownership of the memory
> object so the client cannot unmap while the server is operating on it?

I don't understand your example.

Neal




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