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Date: Thu, 17 Sep 2015 06:54:49 -0700
From: Greg KH <gregkh@linuxfoundation.org>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Dmitry Vyukov <dvyukov@google.com>, Jiri Slaby <jslaby@suse.com>,
        Linux kernel mailing list <linux-kernel@vger.kernel.org>,
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        Alexander Potapenko <glider@google.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Hans Boehm <hboehm@google.com>
Subject: Re: [PATCH v2] tty: fix data race in flush_to_ldisc
Message-ID: <20150917135449.GB26495@kroah.com>
References: <1442486376-115369-1-git-send-email-dvyukov@google.com>
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 <CAKU3ayVt3Jb3tH8Mq3udM7VpChhN_v1s0-h8E66rdj4u6QcOBg@mail.gmail.com>
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On Thu, Sep 17, 2015 at 09:18:11AM -0400, Peter Hurley wrote:
> On Thu, Sep 17, 2015 at 8:53 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > On Thu, Sep 17, 2015 at 12:39:36PM +0200, Dmitry Vyukov wrote:
> >> flush_to_ldisc reads port->itty and checks that it is not NULL,
> >> concurrently release_tty sets port->itty to NULL. It is possible
> >> that flush_to_ldisc loads port->itty once, ensures that it is
> >> not NULL, but then reloads it again and uses. The second load
> >> can already return NULL, which will cause a crash.
> >>
> >> Use READ_ONCE to read port->itty.
> >>
> >> The data race was found with KernelThreadSanitizer (KTSAN).
> >>
> >> Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
> >
> > You sent 3 patches here, but no hint as to what order they need to be
> > applied in.  Please resend them as a patch series (i.e. 1/3, 2/3, 3/3)
> > so they can be applied correctly.
> 
> Greg,
> 
> I don't think these 3 patches are dependent on each other; I think they
> can be applied in any order.

How do I know that?  :)