From nobody Mon Sep 8 08:51:28 2025 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 55213C6FA8B for ; Tue, 13 Sep 2022 14:55:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234802AbiIMOyK (ORCPT ); Tue, 13 Sep 2022 10:54:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231283AbiIMOtp (ORCPT ); Tue, 13 Sep 2022 10:49:45 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 838A27199D; Tue, 13 Sep 2022 07:25:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BB363B80F00; Tue, 13 Sep 2022 14:25:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14A36C433C1; Tue, 13 Sep 2022 14:25:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079137; bh=PMnhD7i5G1Fab9VXpL26O+52Yn0vZi3pZ7kFqp2XxSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zas2inrFpQDADnAtReSqXlzMnEYsLnxJEWNo7wIi2tgoGCyLptXmjvGdphTV3QR+/ uazM1gImJl7hB27Rncdj7t+JeuZDQVKivNs1+of7i/+DwqRcLcOWSgZtx2v13+X6k7 24EHTfi111sDGa21h1nM5fB59E+L85EGTr8jWubI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Eric Dumazet , Neal Cardwell , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 018/108] tcp: annotate data-race around challenge_timestamp Date: Tue, 13 Sep 2022 16:05:49 +0200 Message-Id: <20220913140354.367883633@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140353.549108748@linuxfoundation.org> References: <20220913140353.549108748@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Eric Dumazet [ Upstream commit 8c70521238b7863c2af607e20bcba20f974c969b ] challenge_timestamp can be read an written by concurrent threads. This was expected, but we need to annotate the race to avoid potential issu= es. Following patch moves challenge_timestamp and challenge_count to per-netns storage to provide better isolation. Fixes: 354e4aa391ed ("tcp: RFC 5961 5.2 Blind Data Injection Attack Mitigat= ion") Reported-by: syzbot Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp_input.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f4e00ff909da3..ff10edc85d648 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3484,11 +3484,11 @@ static void tcp_send_challenge_ack(struct sock *sk,= const struct sk_buff *skb) =20 /* Then check host-wide RFC 5961 rate limit. */ now =3D jiffies / HZ; - if (now !=3D challenge_timestamp) { + if (now !=3D READ_ONCE(challenge_timestamp)) { u32 ack_limit =3D READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); u32 half =3D (ack_limit + 1) >> 1; =20 - challenge_timestamp =3D now; + WRITE_ONCE(challenge_timestamp, now); WRITE_ONCE(challenge_count, half + prandom_u32_max(ack_limit)); } count =3D READ_ONCE(challenge_count); --=20 2.35.1