From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794060867; b=DGtrHqjXWh2eWYH1WIMdm42neeOEhxQiWFPhSLG5PGAu2N5kO5J6JcQLUXZZY1VX9dI2 g8s+6YF++k9EoUzPvjV5pCUrvducYwkpszDsJy1JeLtBKWZDWzcV/+IgyNbAHd92riMzj rrWvNanZK9w2Z7Ni/PSXpByDUmANpg+aWpqpl7Xc9pxAf+8NatSxYsLKoHNPEec1O/opl Lp9GpNzNTt6qsIC4oY2jzWuG4Q7Fg8gYLk1bRY6TTt2inaBEK4sMdnKDv7PTx96vDcGJ1 NOJqHUbUXym7M2a6BaBqTHA9GOw939c6ygtXF4h099rlOMEbueUH4uW4l4d2JPDo86w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794060867; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=mCdchWMAx0EI7hEa/1sgDBgoOLk45H0qgMxGG8Rz1ds=; b=uRSoIfZXQ2wok3vkA9k5IQt5VUzk9cnrfUWXgvoPc82/xfITJZJX5stwj7SmVtbktDjv 9MKRTBaDL8XUdWdjRllD/6sNjQBFh/CCTTlYDi3HuXuYcf0VzQr8i1HrIXyWy1aymuWnD Q5tBwsfiAzRHLL+C+nycKss+xIP3KtZq5YTBPzMrkRH4JPHfpzWfK5sgyX81TiUMvzUXy x9PE7LPxQwpc1o+wSlxohzOjOpHVYurdcIf/EIOX0s9s2CIPijXXIbrB7yKGjYxzoeXJb Vy6PELfopPp6wDEEi4QFaK/2EX9vC50i1kdAgnGIoZF0jhHo/ViJq06yl0nZfnKOazA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=YqlQhC5N; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0ED2A606D816; Sat, 7 Nov 2026 14:14:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=YqlQhC5N Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFAE81F0089F; Sat, 7 Nov 2026 14:14:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794060866; bh=mCdchWMAx0EI7hEa/1sgDBgoOLk45H0qgMxGG8Rz1ds=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YqlQhC5NI9UfuRBDQukmNBV3chV07Y4vNCSQm1ZHhMMnP2yqd0RMqMOzMndDBLshU Areb1ZPATGIlnT7vpMrYtCLzSOZiYTIlX0biY64ee2ckiyeV8gCTN2G2NZyt9L9I0Y t2F29YLP0KW66os9L8qCM2BsTliQl4aGDUmLxCYM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florian Westphal , Minghao Zhang , Jianjun Chen , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.12 0247/1536] netfilter: conntrack: tcp: use UNACK timeout for non-closing RST packets Date: Sat, 7 Nov 2026 08:37:43 -0500 Message-ID: <20261107135004.618250669@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Minghao Zhang [ Upstream commit bf80e6802273a900311b44e47c9b1a59c6d2473c ] Commit be0502a3f2e9 ("netfilter: conntrack: tcp: only close if RST matches exact sequence") keeps an established conntrack entry in ESTABLISHED when an in-window RST does not match the expected sequence number exactly, so the endpoint can validate the RST with a challenge ACK. The timeout selection nevertheless uses the CLOSE timeout for every RST packet. The bug is that timeout selection is based on the packet type, not on the state transition result: even when RST validation keeps new_state in ESTABLISHED, the timeout is still forced to TCP_CONNTRACK_CLOSE. Linux TCP independently rate limits challenge ACKs per socket. A second non-exact RST can therefore arrive after the first challenge ACK has restored the timeout but before the rate limit expires. The second RST lowers the timeout to 10 seconds again while the endpoint suppresses the second challenge ACK, allowing the conntrack entry to expire while both TCP endpoints remain established. Using the ESTABLISHED timeout for such RSTs would avoid this short expiration window, but it could also retain stale entries for the five-day default because conntrack cannot reliably match the endpoint's exact TCP state. Use the UNACK timeout for RST packets that leave the conntrack entry in TCP_CONNTRACK_ESTABLISHED. Exact-match RSTs and accepted RST packet trains still fall through to timeouts[new_state], which preserves the CLOSE timeout when conntrack accepts the RST as closing the flow. This avoids the aggressive 10-second expiration window for non-exact RSTs while preserving the short timeout for RSTs that conntrack accepts as closing the flow. Suggested-by: Florian Westphal Reported-by: Minghao Zhang Reported-by: Jianjun Chen Signed-off-by: Minghao Zhang Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_proto_tcp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 91da35e2b0d8d..456721e40ed0c 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -1325,8 +1325,9 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct, if (ct->proto.tcp.retrans >= tn->tcp_max_retrans && timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) timeout = timeouts[TCP_CONNTRACK_RETRANS]; - else if (unlikely(index == TCP_RST_SET)) - timeout = timeouts[TCP_CONNTRACK_CLOSE]; + else if (unlikely(index == TCP_RST_SET && + new_state == TCP_CONNTRACK_ESTABLISHED)) + timeout = timeouts[TCP_CONNTRACK_UNACK]; else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) & IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) -- 2.53.0