linux-kernel - Re: [PATCH v2] w1: do not unlock unheld list_mutex in __w1_remove_master

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Message-ID: <20140506234930.GU21508@spacedout.fries.net>
Date:	Tue, 6 May 2014 18:49:30 -0500
From:	David Fries <David@...es.net>
To:	Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:	Evgeniy Polyakov <zbr@...emap.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: Re: [PATCH v2] w1: do not unlock unheld list_mutex in
 __w1_remove_master_device()

Acked-by: David Fries <david@...es.net>

On Wed, May 07, 2014 at 01:26:04AM +0400, Alexey Khoroshilov wrote:
> w1_process_callbacks() expects to be called with dev->list_mutex held,
> but it is the fact only in w1_process(). __w1_remove_master_device()
> calls w1_process_callbacks() after it releases list_mutex.
> 
> The patch fixes __w1_remove_master_device() to acquire list_mutex
> for w1_process_callbacks().
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
> ---
>  drivers/w1/w1.c     | 2 ++
>  drivers/w1/w1_int.c | 4 ++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
> index ff52618cafbe..5d7341520544 100644
> --- a/drivers/w1/w1.c
> +++ b/drivers/w1/w1.c
> @@ -1078,6 +1078,8 @@ static void w1_search_process(struct w1_master *dev, u8 search_type)
>   * w1_process_callbacks() - execute each dev->async_list callback entry
>   * @dev: w1_master device
>   *
> + * The w1 master list_mutex must be held.
> + *
>   * Return: 1 if there were commands to executed 0 otherwise
>   */
>  int w1_process_callbacks(struct w1_master *dev)
> diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
> index 9b084db739c7..728039d2efe1 100644
> --- a/drivers/w1/w1_int.c
> +++ b/drivers/w1/w1_int.c
> @@ -219,9 +219,13 @@ void __w1_remove_master_device(struct w1_master *dev)
>  
>  		if (msleep_interruptible(1000))
>  			flush_signals(current);
> +		mutex_lock(&dev->list_mutex);
>  		w1_process_callbacks(dev);
> +		mutex_unlock(&dev->list_mutex);
>  	}
> +	mutex_lock(&dev->list_mutex);
>  	w1_process_callbacks(dev);
> +	mutex_unlock(&dev->list_mutex);
>  
>  	memset(&msg, 0, sizeof(msg));
>  	msg.id.mst.id = dev->id;
> -- 
> 1.8.3.2

-- 
David Fries <david@...es.net>    PGP pub CB1EE8F0
http://fries.net/~david/
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