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 C20DAECAAA1 for ; Tue, 6 Sep 2022 13:34:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240549AbiIFNeM (ORCPT ); Tue, 6 Sep 2022 09:34:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240600AbiIFNdl (ORCPT ); Tue, 6 Sep 2022 09:33:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B16DF78595; Tue, 6 Sep 2022 06:33:02 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 924C261545; Tue, 6 Sep 2022 13:33:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A4BDC433D6; Tue, 6 Sep 2022 13:33:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662471181; bh=poKzl3Pl2LOmQJVEYr48xuIcZzoS+tJ8maoGqkhkdRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2RpzXzxO5zStLcMGwFHYDGTJORHVTH5MGf4ZVC0sZe9sXFuYYMNfubOCPRtdKQfh5 l/Yf54OaBUNvz/9zeNxaggagtoEyaM7AxdEcNKcZmyMqakgFTlvkOnxl8JmIbBOovz WefLRSeV7yJuA4F5RqJ0mHSDGK694g3iER3zxHeE= 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 5.10 18/80] tcp: annotate data-race around challenge_timestamp Date: Tue, 6 Sep 2022 15:30:15 +0200 Message-Id: <20220906132817.705298612@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220906132816.936069583@linuxfoundation.org> References: <20220906132816.936069583@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 issues. 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 Mitigation") 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 41b44b311e8a0..e62500d6fe0d0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3599,11 +3599,11 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb) /* Then check host-wide RFC 5961 rate limit. */ now = jiffies / HZ; - if (now != challenge_timestamp) { + if (now != READ_ONCE(challenge_timestamp)) { u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); u32 half = (ack_limit + 1) >> 1; - challenge_timestamp = now; + WRITE_ONCE(challenge_timestamp, now); WRITE_ONCE(challenge_count, half + prandom_u32_max(ack_limit)); } count = READ_ONCE(challenge_count); -- 2.35.1