From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5477E31AAAF; Thu, 2 Jul 2026 16:39:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010375; cv=none; b=qKQkXDcK59RZvABJczBXAJh2tx7YKvafsGTZmvs0k58tyX/66lJjxP5EzK0dczjDlvwvZ9TBzfku5BIcLADWx0I6jgeiyo1tXTUdaPX7xa9ifnM2mVRwQ2S8Gw1AorWVK05Fywh46XeI56DCm9nOy2xwmKVMVAFDN3VC1ucqjJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010375; c=relaxed/simple; bh=Xz4CIugpwgLTczKy9nLtOKTeso+N1qxl+Qi7BTEZxG4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GrEdhZCmw/ptDaWOo09TyyJJ5EvxI88T77m3HdHBjxNLphrpMYq8Nj8ux7nJZdZm4QRXr60H5Nya8UCReCztLmJYH+sS0lePXmFRVrNPweX5eEH50JQqhS1YGij6UOxaQTvFfB4ZRoIM6WnClCvbb/b1FQPZ3KTTKP+eiwU4UHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BkFYk+1y; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="BkFYk+1y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8D921F000E9; Thu, 2 Jul 2026 16:39:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783010374; bh=cq0NHZJNOcJW3GekgN/qYagTUo31KUXyWpExZhwV0Xw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BkFYk+1yFLQZcy8m323Mh8y23daexrC7uWSOb08OkV8vuIQhvUGSwNb0nrdAbKztA SjekAXrAzXcQUAFrA53Ceso4uBUtquxGu1+T1OyuS545oa//UNhoMz8vfDIUl61zjF kAbsAYfMHIDLiGas9HiTvc6YbzbuxF6PVeZFWa98= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xin Long , Marcelo Ricardo Leitner , Jakub Kicinski , Alexander Martyniuk Subject: [PATCH 6.12 085/204] sctp: disable BH before calling udp_tunnel_xmit_skb() Date: Thu, 2 Jul 2026 18:19:02 +0200 Message-ID: <20260702155120.445643512@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155118.667618796@linuxfoundation.org> References: <20260702155118.667618796@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long commit 2cd7e6971fc2787408ceef17906ea152791448cf upstream. udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with BH disabled. After commit 6f1a9140ecda ("add xmit recursion limit to tunnel xmit functions"), on the path: udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit() dev_xmit_recursion_inc()/dec() must stay balanced on the same CPU. Without local_bh_disable(), the context may move between CPUs, which can break the inc/dec pairing. This may lead to incorrect recursion level detection and cause packets to be dropped in ip(6)_tunnel_xmit() or __dev_queue_xmit(). Fix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths. In my testing, after enabling the SCTP over UDP: # ip net exec ha sysctl -w net.sctp.udp_port=9899 # ip net exec ha sysctl -w net.sctp.encap_port=9899 # ip net exec hb sysctl -w net.sctp.udp_port=9899 # ip net exec hb sysctl -w net.sctp.encap_port=9899 # ip net exec ha iperf3 -s - without this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 37.2 MBytes 31.2 Mbits/sec sender [ 5] 0.00-10.00 sec 37.1 MBytes 31.1 Mbits/sec receiver - with this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec sender [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec receiver Fixes: 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions") Fixes: 046c052b475e ("sctp: enable udp tunneling socks") Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/c874a8548221dcd56ff03c65ba75a74e6cf99119.1776017727.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Alexander Martyniuk Signed-off-by: Greg Kroah-Hartman --- net/sctp/ipv6.c | 2 ++ net/sctp/protocol.c | 2 ++ 2 files changed, 4 insertions(+) --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -261,9 +261,11 @@ static int sctp_v6_xmit(struct sk_buff * skb_set_inner_ipproto(skb, IPPROTO_SCTP); label = ip6_make_flowlabel(sock_net(sk), skb, fl6->flowlabel, true, fl6); + local_bh_disable(); udp_tunnel6_xmit_skb(dst, sk, skb, NULL, &fl6->saddr, &fl6->daddr, tclass, ip6_dst_hoplimit(dst), label, sctp_sk(sk)->udp_port, t->encap_port, false); + local_bh_enable(); return 0; } --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -1086,9 +1086,11 @@ static inline int sctp_v4_xmit(struct sk skb_reset_inner_mac_header(skb); skb_reset_inner_transport_header(skb); skb_set_inner_ipproto(skb, IPPROTO_SCTP); + local_bh_disable(); udp_tunnel_xmit_skb(dst_rtable(dst), sk, skb, fl4->saddr, fl4->daddr, dscp, ip4_dst_hoplimit(dst), df, sctp_sk(sk)->udp_port, t->encap_port, false, false); + local_bh_enable(); return 0; }