Date: Sat, 16 Mar 2013 21:32:21 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <andi@firstfloor.org>,
        Lucas De Marchi <lucas.de.marchi@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Paul Mackerras <paulus@samba.org>, david@gibson.dropbear.id.au,
        Kees Cook <keescook@chromium.org>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        "Rafael J. Wysocki" <rjw@sisk.pl>, Feng Hong <hongfeng@marvell.com>,
        Lucas De Marchi <lucas.demarchi@profusion.mobi>
Subject: Re: [PATCH 0/2] finx argv_split() vs sysctl race
Message-ID: <20130316203221.GT11268@two.firstfloor.org>
References: <20130312182210.GA15862@redhat.com>
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 <20130312191118.GA17439@redhat.com>
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 <20130312203514.GA23488@redhat.com>
 <20130313174641.GA28083@redhat.com>
 <20130313174705.GB28083@redhat.com>
 <20130314152819.7fb1242b493e8bad2d34671b@linux-foundation.org>
 <20130315163916.GA31995@redhat.com>
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On Sat, Mar 16, 2013 at 09:23:27PM +0100, Oleg Nesterov wrote:
> On 03/15, Oleg Nesterov wrote:
> >
> > To remind, say, argv_split(poweroff_cmd) can race with sysctl changing this
> > string, in this case it can write to the memory after argv[] array. We can
> > fix this, or we can rewrite argv_split/free:
> 
> OK, please see 1/2.
> 
> And this reminds me about set_task_comm() which pretends it does something
> meaningful for the reader of the mutable ->comm, see the offtopic 2/2.

I had "rcu strings" to handle the sysctl string race problem in a
generic way some time ago.

http://lwn.net/Articles/368684/

Unfortunately never made it in. Perhaps it should be revisited.
In fact I believe the old patchkit fixed the reboot command race.

-andi
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