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 CFCB6C433FE for ; Wed, 16 Nov 2022 17:00:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233578AbiKPRAB (ORCPT ); Wed, 16 Nov 2022 12:00:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233518AbiKPQ7x (ORCPT ); Wed, 16 Nov 2022 11:59:53 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F473DF71 for ; Wed, 16 Nov 2022 08:59:52 -0800 (PST) From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668617990; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k8bdWLa7a0CfQJPJM9b7nroRcd000IAwQvQ4fN3pgNU=; b=VVTK7mse5s54n+mAkC1YYZKR0bprmjywaizjtOHXj0jUMVPcogaHZy0I1Qz4gzud54Ed3z dtiXgHHuQUmt0hjPH0JT5RBXKjnTWDf7kJR5YPBvGVQWu1falo4R/bkOq2M51fd/RNVQs+ tUgxF4lwj0DNpwHzu6RebUrAU6DZHViGfjT5O8pEijilIGVi5HIIEU/Q/6gWEfT1WvcXzU vhAbqAfBdCp8Ve34By3OA1uB5p+H8Kl2CzYesOIW8rn3H7YHYCYDwTFFQ2BacdXbvxsqvX ck6amsIRTPM0V6acAt4N9FYaD/avT7DCwiEKVIKrxoL+++Rvksb/jHF4IpRhsg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668617990; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k8bdWLa7a0CfQJPJM9b7nroRcd000IAwQvQ4fN3pgNU=; b=PSOieoNh5Q77Iu5AMHHVdf+PsuUCe3FfHS09zebA6393Hm5sWSO4sWp4xlRCNSYqHw4+hZ yPGB2mn5OrVhucCA== To: netdev@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Juhee Kang , Thomas Gleixner , Kurt Kanzenbach , Sebastian Andrzej Siewior Subject: [PATCH net 5/5] hsr: Synchronize sequence number updates. Date: Wed, 16 Nov 2022 17:59:43 +0100 Message-Id: <20221116165943.1776754-6-bigeasy@linutronix.de> In-Reply-To: <20221116165943.1776754-1-bigeasy@linutronix.de> References: <20221116165943.1776754-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org hsr_register_frame_out() compares new sequence_nr vs the old one recorded in hsr_node::seq_out and if the new sequence_nr is higher then it will be written to hsr_node::seq_out as the new value. This operation isn't locked so it is possible that two frames with the same sequence number arrive (via the two slave devices) and are fed to hsr_register_frame_out() at the same time. Both will pass the check and update the sequence counter later to the same value. As a result the content of the same packet is fed into the stack twice. This was noticed by running ping and observing DUP being reported from time to time. Instead of using the hsr_priv::seqnr_lock for the whole receive path (as it is for sending in the master node) ensure that the id is only updated based on the expected old value. Use cmpxchg() to only update sequence number if it is the old value, that was also used for comparison. Fixes: f421436a591d3 ("net/hsr: Add support for the High-availability Seaml= ess Redundancy protocol (HSRv0)") Signed-off-by: Sebastian Andrzej Siewior --- net/hsr/hsr_framereg.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c index 9b8eaebce2549..7a9d4d36f114d 100644 --- a/net/hsr/hsr_framereg.c +++ b/net/hsr/hsr_framereg.c @@ -453,13 +453,19 @@ void hsr_register_frame_in(struct hsr_node *node, str= uct hsr_port *port, int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node, u16 sequence_nr) { - if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]) && + u16 old_seq; +again: + old_seq =3D READ_ONCE(node->seq_out[port->type]); + + if (seq_nr_before_or_eq(sequence_nr, old_seq) && time_is_after_jiffies(node->time_out[port->type] + msecs_to_jiffies(HSR_ENTRY_FORGET_TIME))) return 1; =20 + if (cmpxchg(&node->seq_out[port->type], old_seq, sequence_nr) !=3D old_se= q) + goto again; + node->time_out[port->type] =3D jiffies; - node->seq_out[port->type] =3D sequence_nr; return 0; } =20 --=20 2.38.1