linux-kernel - Re: [PATCH 4.19 84/86] dm integrity: fix integrity recalculation that is improperly skipped

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Message-ID: <20200728002416.GB28830@redhat.com>
Date:   Mon, 27 Jul 2020 20:24:16 -0400
From:   Mike Snitzer <snitzer@...hat.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     Pavel Machek <pavel@...x.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 4.19 84/86] dm integrity: fix integrity recalculation
 that is improperly skipped

On Mon, Jul 27 2020 at  7:31pm -0400,
Sasha Levin <sashal@...nel.org> wrote:

> On Mon, Jul 27, 2020 at 10:56:35PM +0200, Pavel Machek wrote:
> >Hi!
> >
> >>From: Mikulas Patocka <mpatocka@...hat.com>
> >>
> >>commit 5df96f2b9f58a5d2dc1f30fe7de75e197f2c25f2 upstream.
> >>
> >>Commit adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 ("dm: report suspended
> >>device during destroy") broke integrity recalculation.
> >>
> >>The problem is dm_suspended() returns true not only during suspend,
> >>but also during resume. So this race condition could occur:
> >>1. dm_integrity_resume calls queue_work(ic->recalc_wq, &ic->recalc_work)
> >>2. integrity_recalc (&ic->recalc_work) preempts the current thread
> >>3. integrity_recalc calls if (unlikely(dm_suspended(ic->ti))) goto unlock_ret;
> >>4. integrity_recalc exits and no recalculating is done.
> >>
> >>To fix this race condition, add a function dm_post_suspending that is
> >>only true during the postsuspend phase and use it instead of
> >>dm_suspended().
> >>
> >>Signed-off-by: Mikulas Patocka <mpatocka redhat com>
> >
> >Something is wrong with signoff here...
> 
> Heh, and the same thing happened with the stable tag:
> 
> 	Cc: stable vger kernel org # v4.18+
> 
> But given that this is the way the upstream commit looks like we can't
> do much here.

Hmm, not sure what happened on the Signed-off-by and Cc for commit
5df96f2b9f.  Sorry about this!