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

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Date:   Sun, 8 Dec 2019 16:22:18 +0000
From:   Ido Schimmel <idosch@...lanox.com>
To:     Ben Hutchings <ben@...adent.org.uk>
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, 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