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Date: Wed, 19 Oct 2016 18:44:29 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Leon Yu <chianglungyu@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>, Kees Cook <keescook@chromium.org>,
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        Mateusz Guzik <mguzik@redhat.com>,
        Janis Danisevskis <jdanis@google.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] proc: fix NULL dereference when reading
        /proc/<pid>/auxv
Message-ID: <20161019164428.GE21216@redhat.com>
References: <1476885580-7612-1-git-send-email-chianglungyu@gmail.com> <20161019141346.GJ7517@dhcp22.suse.cz> <20161019161207.GD21216@redhat.com> <20161019161731.GK24393@dhcp22.suse.cz>
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On 10/19, Michal Hocko wrote:
>
> On Wed 19-10-16 18:12:08, Oleg Nesterov wrote:
> > On 10/19, Michal Hocko wrote:
> > >
> > > Why would we even want to open that file if there is no mm struct?
> >
> > Agreed this is strange, but I am not sure we can change this old
> > behaviour. Say, cat /proc/$pid-of-kthread/mem doesn't fail, it shows
> > the "empty mm".
>
> What kind of application would break?

I have no idea, probably nobody will ever notice this change, just
I am always nervous when it comes to user-visible changes.

But why do we want this change? Not that I am going to argue if you
submit a patch, but personally I see no real point.

Oleg.