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Date: Wed, 26 Jan 2011 16:46:50 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Kees Cook <kees.cook@canonical.com>
Cc: linux-kernel@vger.kernel.org, Rusty Russell <rusty@rustcorp.com.au>,
        Tejun Heo <tj@kernel.org>, Marcus Meissner <meissner@suse.de>,
        Jason Wessel <jason.wessel@windriver.com>,
        Eugene Teo <eugeneteo@kernel.org>, Joe Perches <joe@perches.com>,
        Bjorn Helgaas <bjorn.helgaas@hp.com>, Len Brown <len.brown@intel.com>,
        Changli Gao <xiaosuo@gmail.com>,
        Dan Rosenberg <drosenberg@vsecurity.com>
Subject: Re: [PATCH] use %pK for /proc/kallsyms and /proc/modules
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On Wed, 26 Jan 2011 16:29:36 -0800
Kees Cook <kees.cook@canonical.com> wrote:

> > > Note that this changes %x to %p, so some legitimately 0 values in
> > > /proc/kallsyms would have changed from 00000000 to "(null)". To avoid
> > > this, "(null)" is not used when using the "K" format. Anything parsing
> > > such addresses should have no problem with this change. (Thanks to Joe
> > > Perches for the suggestion.)
> > 
> > OK, so what applications did this patch just break?
> 
> I'm not aware of any breakage as a result of this yet.

There will be some - there always are :( But users will only see
problems if they've set kptr_restrict.

Which they shall do.  How come we defaulted kptr_restrict to "true"?