From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C1CBA2F28; Mon, 10 Mar 2025 18:18:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741630693; cv=none; b=dR1PyusjRdaTOEEaWeNt9OGnrMg5yLTdZAMkEDm1mA62M0zvMUjzbr7d+f1CIPcbEjlfORxcEphyyyoTzW6AuKYk4uChrZJMswl3692XkXV8x+xPVL7dH6XKIxpIpaNgNfFzYCUhd1+bGtxYs2YQrLHPbShivWTdCFwo0hICUMY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741630693; c=relaxed/simple; bh=TZTeoR7P6XiFAvMuIdBwZxaGt50jW0eX+nKc+sr3Sjo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aYOlgAt4M/U4+NFSrFyBQCUZqKNU6IazANEfDy/RGq8GCvBKdCD7PMeYSh0ihi7GnMETEITPPJhl2gn+zoip8YqzPG+ZqQ+XEl1Z6uEizK829rgcJ7foO10ATtfnAvwXFQ6d0YRT7WNRC08oGgjmZBLM1xmoJGvH8q7ucfBafXw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=L7BuB3Kh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="L7BuB3Kh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0ECAC4CEE5; Mon, 10 Mar 2025 18:18:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741630693; bh=TZTeoR7P6XiFAvMuIdBwZxaGt50jW0eX+nKc+sr3Sjo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L7BuB3KhYdG+8wE2P9unu+J1mVabue2/kiL+Hmj12pcoDyv31KGdB4DyoxgSWQHuV HqrI5TTxeL4olBAO4/pxrZglzNEtI1WKDfrCrNCw3AVZz7WJst59FEngB2hS2CJgm1 CpWsLBnd15w7GhqjRY+NwGb5u3DMGn6aAeuckI44= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wang Hai , Jason Xing , Eric Dumazet , Kuniyuki Iwashima , "David S. Miller" , Sasha Levin Subject: [PATCH 5.15 503/620] tcp: Defer ts_recent changes until req is owned Date: Mon, 10 Mar 2025 18:05:49 +0100 Message-ID: <20250310170605.418854964@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250310170545.553361750@linuxfoundation.org> References: <20250310170545.553361750@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wang Hai [ Upstream commit 8d52da23b6c68a0f6bad83959ebb61a2cf623c4e ] Recently a bug was discovered where the server had entered TCP_ESTABLISHED state, but the upper layers were not notified. The same 5-tuple packet may be processed by different CPUSs, so two CPUs may receive different ack packets at the same time when the state is TCP_NEW_SYN_RECV. In that case, req->ts_recent in tcp_check_req may be changed concurrently, which will probably cause the newsk's ts_recent to be incorrectly large. So that tcp_validate_incoming will fail. At this point, newsk will not be able to enter the TCP_ESTABLISHED. cpu1 cpu2 tcp_check_req tcp_check_req req->ts_recent = rcv_tsval = t1 req->ts_recent = rcv_tsval = t2 syn_recv_sock tcp_sk(child)->rx_opt.ts_recent = req->ts_recent = t2 // t1 < t2 tcp_child_process tcp_rcv_state_process tcp_validate_incoming tcp_paws_check if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) // t2 - t1 > paws_win, failed tcp_v4_do_rcv tcp_rcv_state_process // TCP_ESTABLISHED The cpu2's skb or a newly received skb will call tcp_v4_do_rcv to get the newsk into the TCP_ESTABLISHED state, but at this point it is no longer possible to notify the upper layer application. A notification mechanism could be added here, but the fix is more complex, so the current fix is used. In tcp_check_req, req->ts_recent is used to assign a value to tcp_sk(child)->rx_opt.ts_recent, so removing the change in req->ts_recent and changing tcp_sk(child)->rx_opt.ts_recent directly after owning the req fixes this bug. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai Reviewed-by: Jason Xing Reviewed-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/tcp_minisocks.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index d84b71f70766b..061225d645e6b 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -725,12 +725,6 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, /* In sequence, PAWS is OK. */ - /* TODO: We probably should defer ts_recent change once - * we take ownership of @req. - */ - if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) - WRITE_ONCE(req->ts_recent, tmp_opt.rcv_tsval); - if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { /* Truncate SYN, it is out of window starting at tcp_rsk(req)->rcv_isn + 1. */ @@ -779,6 +773,10 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, if (!child) goto listen_overflow; + if (own_req && tmp_opt.saw_tstamp && + !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) + tcp_sk(child)->rx_opt.ts_recent = tmp_opt.rcv_tsval; + if (own_req && rsk_drop_req(req)) { reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req); inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req); -- 2.39.5