linux-kernel - Re: [PATCH 3.16 43/72] thermal: Fix use-after-free when unregistering thermal zone device

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Message-ID: <92faedffaa625da9d385a6af2e554d8e4744fa7a.camel@decadent.org.uk>
Date:   Sun, 08 Dec 2019 18:09:36 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     Ido Schimmel <idosch@...lanox.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        Denis Kirjanov <kda@...ux-powerpc.org>,
        Jiri Pirko <jiri@...lanox.com>,
        Zhang Rui <rui.zhang@...el.com>,
        "wvw@...gle.com" <wvw@...gle.com>
Subject: Re: [PATCH 3.16 43/72] thermal: Fix use-after-free when
 unregistering thermal zone device

On Sun, 2019-12-08 at 16:22 +0000, Ido Schimmel wrote:
> On Sun, Dec 08, 2019 at 01:53:27PM +0000, Ben Hutchings wrote:
> > 3.16.79-rc1 review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Ido Schimmel <idosch@...lanox.com>
> > 
> > commit 1851799e1d2978f68eea5d9dff322e121dcf59c1 upstream.
> > 
> > thermal_zone_device_unregister() cancels the delayed work that polls the
> > thermal zone, but it does not wait for it to finish. This is racy with
> > respect to the freeing of the thermal zone device, which can result in a
> > use-after-free [1].
> > 
> > Fix this by waiting for the delayed work to finish before freeing the
> > thermal zone device. Note that thermal_zone_device_set_polling() is
> > never invoked from an atomic context, so it is safe to call
> > cancel_delayed_work_sync() that can block.
> 
> Ben,
> 
> Wei Wang (copied) found a problem with this patch and fixed it:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=163b00cde7cf2206e248789d2780121ad5e6a70b
> 
> I believe you should take both patches to your tree.

Thanks, I will add that now that it is in Linus's tree.

Ben.

-- 
Ben Hutchings
Never attribute to conspiracy what can adequately be explained
by stupidity.



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