linux-kernel - RE: [PATCH 10/10] mei: bus: Check for still connected devices in mei_cl_bus_dev

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Message-ID: <CY5PR11MB6366452655D223572AAF11D2ED7BA@CY5PR11MB6366.namprd11.prod.outlook.com>
Date: Wed, 25 Jun 2025 10:25:38 +0000
From: "Usyskin, Alexander" <alexander.usyskin@...el.com>
To: Hans de Goede <hansg@...nel.org>, Sakari Ailus
	<sakari.ailus@...ux.intel.com>, Stanislaw Gruszka
	<stanislaw.gruszka@...ux.intel.com>
CC: Arnd Bergmann <arnd@...db.de>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 10/10] mei: bus: Check for still connected devices in
 mei_cl_bus_dev_release()

> Subject: [PATCH 10/10] mei: bus: Check for still connected devices in
> mei_cl_bus_dev_release()
> 
> mei_cl_bus_dev_release() also frees the mei-client (struct mei_cl)
> belonging to the device being released.
> 
> If there are bugs like the just fixed bug in the ACE/CSI2 mei drivers,
> the mei-client being freed might still be part of the mei_device's
> file_list and iterating over this list after the freeing will then trigger
> a use-afer-free bug.
> 
> Add a check to mei_cl_bus_dev_release() to make sure that the to-be-freed
> mei-client is not on the mei_device's file_list.
> 

Reviewed-by: Alexander Usyskin <alexander.usyskin@...el.com>

> Signed-off-by: Hans de Goede <hansg@...nel.org>
> ---
>  drivers/misc/mei/bus.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
> index 67176caf5416..1958c043ac14 100644
> --- a/drivers/misc/mei/bus.c
> +++ b/drivers/misc/mei/bus.c
> @@ -1301,10 +1301,16 @@ static void mei_dev_bus_put(struct mei_device
> *bus)
>  static void mei_cl_bus_dev_release(struct device *dev)
>  {
>  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
> +	struct mei_device *mdev = cldev->cl->dev;
> +	struct mei_cl *cl;
> 
>  	mei_cl_flush_queues(cldev->cl, NULL);
>  	mei_me_cl_put(cldev->me_cl);
>  	mei_dev_bus_put(cldev->bus);
> +
> +	list_for_each_entry(cl, &mdev->file_list, link)
> +		WARN_ON(cl == cldev->cl);
> +
>  	kfree(cldev->cl);
>  	kfree(cldev);
>  }
> --
> 2.49.0