From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CFBE83D64 for ; Fri, 18 Aug 2023 18:42:36 +0000 (UTC) Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C021335A5; Fri, 18 Aug 2023 11:42:35 -0700 (PDT) Received: by mail-pj1-x1030.google.com with SMTP id 98e67ed59e1d1-26814e27a9eso841072a91.0; Fri, 18 Aug 2023 11:42:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692384155; x=1692988955; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=tC87ytfbpYDqxm55kNo/dnnHD896FFpzuLkzfJ0vw34=; b=HHHeW0kMnjD2rzZTTJouYt54sd4ScQ5bQ3ZReaKfwC9Nqqpjvo9vuNoKMdhRslVIfK eapb93kt5LRZzlpT552Wbt5w2FfYcPSxvrMeNGzMB3swYPkOq54Wp02AcoPDC8cQfimH fstd9Yh/Qpo9y8FF24cP90fAy3/tdrQEkTsRmcJmR3zQDio4CZQVoSQ7NeHkzLneZygU Ogez300R3FCO3/5I8vm9iL9EPzQk0VUaW+SHBahA65WasB2SPowHq3MgbYgWm4/PRcJr ZoKe1NJAfmy6yqpwZ3idH7FHG98mDVzAYkxvB7aXbWhxqGQh1dFg6E2jUGFL+9KIHhTD /qzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692384155; x=1692988955; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=tC87ytfbpYDqxm55kNo/dnnHD896FFpzuLkzfJ0vw34=; b=jRVM0w2lwDIAmvZKt6hp6PTIjUmpvNmCOFDu8RZa7Zsi/cUnpalAvCUpKsdsK/tZKD OTEBL/3FdB2hpeSjJLX5HbnQsMugdbydSK/bww6fuOdFtCsgzSuQ8XpXHBTvHQdRTaR5 7FmGHY1Kyumi8DM+h8rebM4+4CFs8n4rn4i2oXwCvyyxklOrufao8qBGDnx/oT2txfIP y3t8mHqC0W7YLLAX/Xxm1M8i/hZcjGKtY7LRUuMmeLQ1q/wTNceC2nwAtqzZR3mxKO6c 19ZWKyqJqU5brpS5ZCQSQeC26oaPcGguxkPQhY27doHOYx+Vo8fC2PMOgnLU/gJL/2aj Vawg== X-Gm-Message-State: AOJu0YxcKCtvIZMD2CpdY8seZzJjIyPCrnw11ohkXXO6SMfATBf1WMcu 6RHGMpC/G2Xxmul/draY0gqExf4cxOzStQ== X-Google-Smtp-Source: AGHT+IEqoWGs4DFszNmL/EEjujikAHCo4BP0FuNfQx6BUjSeFkvIEu1uDom2G7LkB+iEZRGhfdCM5A== X-Received: by 2002:a17:90a:8681:b0:267:fba3:ed96 with SMTP id p1-20020a17090a868100b00267fba3ed96mr52088pjn.3.1692384155093; Fri, 18 Aug 2023 11:42:35 -0700 (PDT) Received: from VAN-928222-PC0.fortinet-us.com ([173.214.130.2]) by smtp.gmail.com with ESMTPSA id o4-20020a17090a5b0400b00263b4b1255esm3546721pji.51.2023.08.18.11.42.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Aug 2023 11:42:34 -0700 (PDT) From: Qingjie Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, keescook@chromium.org, johannes@sipsolutions.net, pctammela@mojatatu.com, dhowells@redhat.com, fw@strlen.de, kuniyu@amazon.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, xqjcool@gmail.com Subject: [PATCH] netlink: Fix the netlink socket malfunction due to concurrency Date: Fri, 18 Aug 2023 11:37:11 -0700 Message-ID: <20230818183712.123455-1-xqjcool@gmail.com> X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net The concurrent Invocation of netlink_attachskb() and netlink_recvmsg() on different CPUs causes malfunction of netlink socket. The concurrent scenario of netlink_recvmsg() and netlink_attachskb() as following: CPU A CPU B ======== ======== netlink_recvmsg() netlink_attachskb() [1]bit NETLINK_S_CONGESTED is set netlink_overrun() netlink_rcv_wake() [2]sk_receive_queue is empty clear bit NETLINK_S_CONGESTED [3]NETLINK_F_RECV_NO_ENOBUFS not set set bit NETLINK_S_CONGESTED In this scenario, the socket's receive queue is empty. Additionally, due to the NETLINK_S_CONGESTED flag being set, all packets sent to this socket are discarded. To prevent this situation, we need to introduce a check for whether the socket receive buffer is full before setting the NETLINK_S_CONGESTED flag. Signed-off-by: Qingjie Xing --- net/netlink/af_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 383631873748..80bcce9acbfc 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -352,7 +352,8 @@ static void netlink_overrun(struct sock *sk) struct netlink_sock *nlk = nlk_sk(sk); if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) { - if (!test_and_set_bit(NETLINK_S_CONGESTED, + if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf + && !test_and_set_bit(NETLINK_S_CONGESTED, &nlk_sk(sk)->state)) { sk->sk_err = ENOBUFS; sk_error_report(sk); -- 2.41.0