linux-kernel - Re: [PATCH v4 3/5] net/tcp: Disable TCP-MD5 static key on tcp_md5sig

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Message-ID: <20221118191809.0174f4da@kernel.org>
Date:   Fri, 18 Nov 2022 19:18:09 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Dmitry Safonov <dima@...sta.com>
Cc:     linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Francesco Ruggeri <fruggeri@...sta.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jason Baron <jbaron@...mai.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Salam Noureddine <noureddine@...sta.com>,
        Steven Rostedt <rostedt@...dmis.org>, netdev@...r.kernel.org
Subject: Re: [PATCH v4 3/5] net/tcp: Disable TCP-MD5 static key on
 tcp_md5sig_info destruction

On Tue, 15 Nov 2022 21:19:03 +0000 Dmitry Safonov wrote:
> +	if (!rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) {
> +		if (tcp_md5sig_info_add(sk, sk_gfp_mask(sk, GFP_ATOMIC)))
> +			return -ENOMEM;
> +
> +		if (!static_key_fast_inc_not_negative(&tcp_md5_needed.key.key)) {
> +			struct tcp_md5sig_info *md5sig = tp->md5sig_info;

I don't think sparse will be able to deduce that ->md5sig_info access
is safe here, so could you wrap it up as well? Maybe it wouldn't be 
the worst move to provide a sk_rcu_dereference() or rcu_dereference_sk()
or some such wrapper.

More importantly tho - was the merging part for this patches discussed?
They don't apply to net-next.