From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FB88C433EF for ; Mon, 28 Feb 2022 02:13:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230142AbiB1COS (ORCPT ); Sun, 27 Feb 2022 21:14:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229985AbiB1COR (ORCPT ); Sun, 27 Feb 2022 21:14:17 -0500 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F137145510; Sun, 27 Feb 2022 18:13:36 -0800 (PST) Received: by mail-pg1-x530.google.com with SMTP id t14so7230471pgr.3; Sun, 27 Feb 2022 18:13:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=DtL7SWK21u+xZhbjnZFVcZx7PZjrMA1o1qQEXFS0MNU=; b=BzKpTfnzjJcfZXPaely/HTimgea5Ajt9ht87rUYI2hbwr/Qp6Nkh9oY8eNOOr9o/lE 1GN5hMxgxkyV1QyWFP0FetciKJTWzxFucni7mW8mf/CNa7RaivOqfa5AFhFrRDc0MipG dqmp/lLVJVD2hM5fCZpzkLjmmKD7X6uGSYQey3BDmcJCd1hKSHnC51pfOqLdt13VSgMm N/9t/2TfNUTz9QsTOjjHhOtbdQ8zNzBb3/05LBxrGvwNSC0eidxj6D/HB0oAuIIsJ577 lyI4oxxFUtOkC8DteEbkKlzVwmRPRQdYDaAtRIJCSpLTC4DAXfowRhqDYy3UBG+79uuu TvVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=DtL7SWK21u+xZhbjnZFVcZx7PZjrMA1o1qQEXFS0MNU=; b=sdYXGvGnlIlQaiQubVu1i0qZKAsNgHF30gKL2F23bjPAH5UB1dLNagtyS87X8GG/5z Ondnfoy+OXHUBn4ACYUtdcpkk4geX95gF7qsS6jd5mStVXN+TGhMPDynfGXrQopkOM5Y JWoZ2DSTqhBtFRDVrV4LazZ5uxv5myoYf1ANqHqFhZvG6CMadwghaMQhsghiBrWILOxm D5YRIpDLwlkdLPd3CtryxmzBJIX3FgVUF+m8gmmp1FfGc31mMTBGxjEH0v1gBdX1utqo UtxAeV5dIVSL8RakDO12AN1lTGo0CO7zAsQTwuutQIIxHZy0Q/RZqJThe4B9cg5QHRhg ZSFw== X-Gm-Message-State: AOAM532Aybco/7yUNrqTanOX/2BEPVY5Z2Z7Vh4J45vylDUGrysy8pJe GwH8L5XHJYU7XYEKVE+5AdgQELVr/6Y= X-Google-Smtp-Source: ABdhPJxnFM6IXEA+rP8R+defBg6RvFrhktJtrIXjfp79gGeKIZ8Bl7ONFaaRIU1h9mpCtqTodplfrQ== X-Received: by 2002:a63:27c7:0:b0:343:984e:3428 with SMTP id n190-20020a6327c7000000b00343984e3428mr15538326pgn.528.1646014416397; Sun, 27 Feb 2022 18:13:36 -0800 (PST) Received: from [192.168.86.21] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id m5-20020a056a00080500b004e174acd876sm11141056pfk.216.2022.02.27.18.13.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Feb 2022 18:13:35 -0800 (PST) Message-ID: <872e2596-4d7c-3b91-341c-0db3a3d7fd57@gmail.com> Date: Sun, 27 Feb 2022 18:13:33 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH net-next 18/32] netfilter: egress: avoid a lockdep splat Content-Language: en-US To: Pablo Neira Ayuso , netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org References: <20220109231640.104123-1-pablo@netfilter.org> <20220109231640.104123-19-pablo@netfilter.org> From: Eric Dumazet In-Reply-To: <20220109231640.104123-19-pablo@netfilter.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On 1/9/22 15:16, Pablo Neira Ayuso wrote: > From: Florian Westphal > > include/linux/netfilter_netdev.h:97 suspicious rcu_dereference_check() usage! > 2 locks held by sd-resolve/1100: > 0: ..(rcu_read_lock_bh){1:3}, at: ip_finish_output2 > 1: ..(rcu_read_lock_bh){1:3}, at: __dev_queue_xmit > __dev_queue_xmit+0 .. > > The helper has two callers, one uses rcu_read_lock, the other > rcu_read_lock_bh(). Annotate the dereference to reflect this. > > Fixes: 42df6e1d221dd ("netfilter: Introduce egress hook") > Signed-off-by: Florian Westphal > Signed-off-by: Pablo Neira Ayuso > --- > include/linux/netfilter_netdev.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/netfilter_netdev.h b/include/linux/netfilter_netdev.h > index b71b57a83bb4..b4dd96e4dc8d 100644 > --- a/include/linux/netfilter_netdev.h > +++ b/include/linux/netfilter_netdev.h > @@ -94,7 +94,7 @@ static inline struct sk_buff *nf_hook_egress(struct sk_buff *skb, int *rc, > return skb; > #endif > > - e = rcu_dereference(dev->nf_hooks_egress); > + e = rcu_dereference_check(dev->nf_hooks_egress, rcu_read_lock_bh_held()); > if (!e) > return skb; > It seems other rcu_dereference() uses will also trigger lockdep splat. nft_do_chain() ... if (genbit)     blob = rcu_dereference(chain->blob_gen_1); else    blob = rcu_dereference(chain->blob_gen_0); I wonder how many other places will need a fix ?