netdev - Re: [PATCH net-next] tcp: md5: Handle RCU dereference of md5sig

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Date:   Thu, 21 Dec 2017 14:13:35 -0800
From:   Christoph Paasch <christoph.paasch@...il.com>
To:     Mat Martineau <mathew.j.martineau@...ux.intel.com>
Cc:     netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: md5: Handle RCU dereference of md5sig_info

On Thu, Dec 21, 2017 at 10:29 AM, Mat Martineau
<mathew.j.martineau@...ux.intel.com> wrote:
> Dereference tp->md5sig_info in tcp_v4_destroy_sock() the same way it is
> done in the adjacent call to tcp_clear_md5_list().
>
> Resolves this sparse warning:
>
> net/ipv4/tcp_ipv4.c:1914:17: warning: incorrect type in argument 1 (different address spaces)
> net/ipv4/tcp_ipv4.c:1914:17:    expected struct callback_head *head
> net/ipv4/tcp_ipv4.c:1914:17:    got struct callback_head [noderef] <asn:4>*<noident>
>
> Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
> ---
>  net/ipv4/tcp_ipv4.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index dd945b114215..5d203248123e 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1911,7 +1911,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
>         /* Clean up the MD5 key list, if any */
>         if (tp->md5sig_info) {
>                 tcp_clear_md5_list(sk);
> -               kfree_rcu(tp->md5sig_info, rcu);
> +               kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu);

Acked-by: Christoph Paasch <cpaasch@...le.com>