netdev - Re: [Patch net] tun: fix a memory leak for tfile->tx

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Message-ID: <4f1ddad2-89da-b3e4-5cb1-9b686beb205d@redhat.com>
Date:   Wed, 10 Jan 2018 11:00:10 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Cc:     dvyukov@...gle.com
Subject: Re: [Patch net] tun: fix a memory leak for tfile->tx_array



On 2018年01月10日 08:07, Cong Wang wrote:
> tfile->tun could be detached before we close the tun fd,
> via tun_detach_all(), so it should not be used to check for
> tfile->tx_array.
>
> Use the same logic as in tun_attach(), just test !tfile->deatched.
>
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> Fixes: 1576d9860599 ("tun: switch to use skb array for tx")
> Cc: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
> ---
>   drivers/net/tun.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 4f4a842a1c9c..1a1f834440a6 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile)
>   
>   static void __tun_detach(struct tun_file *tfile, bool clean)
>   {
> +	bool clean_tx_array = !tfile->detached;
>   	struct tun_file *ntfile;
>   	struct tun_struct *tun;
>   
> @@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
>   			    tun->dev->reg_state == NETREG_REGISTERED)
>   				unregister_netdevice(tun->dev);
>   		}
> -		if (tun)
> +		if (clean_tx_array)
>   			skb_array_cleanup(&tfile->tx_array);
>   		sock_put(&tfile->sk);
>   	}

Looks like we may still leak if we do

open
attach
detach
close

Should we do cleanup unconditionally?

Thanks