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Date: Fri, 25 Sep 2026 16:04:53 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Cc: Anastasios Papagiannis <tasos.papagiannnis@gmail.com>,
 linux-mm@kvack.org, liam@infradead.org, bpf@vger.kernel.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/nommu: Reject wrapping ranges in access_remote_vm()
Message-Id: <20260925160453.7e7561edb77b5c4152675f7e@linux-foundation.org>
In-Reply-To: <arZzn0bwWqp7xTE5@gremlin>
References: <20260909064231.18693-1-tasos.papagiannnis@gmail.com>
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On Fri, 25 Sep 2026 14:20:33 +0100 "Lorenzo Stoakes (ARM)" <ljs@kernel.org> wrote:

> BTW always feel free to nag if you're not getting review! Something things
> get missed. (Though I'd say wait at least a couple weeks before doing
> that!)
> 
> On Wed, Sep 09, 2026 at 09:42:31AM +0300, Anastasios Papagiannis wrote:
> > The NOMMU implementation of access_process_vm() rejects address ranges
> > whose end wraps around, but access_remote_vm() bypasses this check even
> > though both functions delegate to __access_remote_vm().
> >
> > Move the wraparound check into __access_remote_vm() so it applies to
> > both entry points.
> >
> > This is originally reported in [1].
> >
> > [1] https://lore.kernel.org/bpf/4ef240a5bea36ff84df9589671367832860795159386a4c8fba546a0fa8b786f@mail.kernel.org/
> 
> Probably better to drop this big and make this a Link: tag.

My scripts (after much recent LLM-driven fancification) made this
change automatically!  It became

Closes: https://lore.kernel.org/bpf/4ef240a5bea36ff84df9589671367832860795159386a4c8fba546a0fa8b786f@mail.kernel.org/ [1]

But scripts didn't figure out how to add a Reported-by: as well.

> >
> > Fixes: f55f199b7d76 ("NOMMU: implement access_remote_vm")
> 
> Cc: stable I think?

Well why.

I see in [1] "causing memory disclosure or a bus fault".  OK, we care
about that.  So the changelog should tell people this very important
info and should explain the circumstances which can lead to the failure.

> > Signed-off-by: Anastasios Papagiannis <tasos.papagiannnis@gmail.com>
> 
> Seems reasonable to me! So:
> 
> Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Cool.