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From: Andreas Gruenbacher <agruen@suse.de>
Organization: SUSE Labs, Novell
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [AppArmor 37/41] AppArmor: Main Part
Date: Fri, 13 Apr 2007 10:48:17 +0200
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On Thursday 12 April 2007 12:37, Alan Cox wrote:
> > +		if (PTR_ERR(sa->name) == -ENOENT && (check & AA_CHECK_FD))
> > +			denied_mask = 0;
>
> Now there is an interesting question. Is PTR_ERR() safe for kernel
> pointers on all platforms or just for user ones ?

It's used for kernel pointers all over the place and mmap also mixes user 
addresses with -Exxx, so it's definitely supposed to work. I'm not sure how 
exactly the topmost page is kept from getting mapped.

Andreas