linux-kernel - Re: [PATCH v2] tty: fix data race in flush_to

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Date:	Thu, 17 Sep 2015 05:53:01 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	peter@...leysoftware.com, jslaby@...e.com,
	linux-kernel@...r.kernel.org, jslaby@...e.cz,
	andreyknvl@...gle.com, kcc@...gle.com, glider@...gle.com,
	paulmck@...ux.vnet.ibm.com, hboehm@...gle.com
Subject: Re: [PATCH v2] tty: fix data race in flush_to_ldisc

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@...gle.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.

thanks,

greg k-h
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