netdev - Re: [PATCH linux-4.4.y/linux-4.9.y v2] slip: stop double free sl->dev in slip

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Date:   Tue, 3 Mar 2020 16:45:45 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     yangerkun <yangerkun@...wei.com>
Cc:     stable@...r.kernel.org, davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH linux-4.4.y/linux-4.9.y v2] slip: stop double free
 sl->dev in slip_open

On Fri, Feb 28, 2020 at 09:40:48PM +0800, yangerkun wrote:
> After include 3b5a39979daf ("slip: Fix memory leak in slip_open error path")
> and e58c19124189 ("slip: Fix use-after-free Read in slip_open") with 4.4.y/4.9.y.
> We will trigger a bug since we can double free sl->dev in slip_open. Actually,
> we should backport cf124db566e6 ("net: Fix inconsistent teardown and release
> of private netdev state.") too since it has delete free_netdev from sl_free_netdev.
> Fix it by delete free_netdev from slip_open.
> 
> Signed-off-by: yangerkun <yangerkun@...wei.com>
> ---
>  drivers/net/slip/slip.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
> index 0f8d5609ed51..d4a33baa33b6 100644
> --- a/drivers/net/slip/slip.c
> +++ b/drivers/net/slip/slip.c
> @@ -868,7 +868,6 @@ err_free_chan:
>  	tty->disc_data = NULL;
>  	clear_bit(SLF_INUSE, &sl->flags);
>  	sl_free_netdev(sl->dev);
> -	free_netdev(sl->dev);

Thanks for this, now queued up.

greg k-h