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 7DD173B7767; Sat, 17 Oct 2026 17:39:16 +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=1792258757; cv=none; b=GcYVOT9nk6sfkC2gsOYq78lCPUmNtPDabMWPMULBAZYsR//wl8DTip6oOVBM1YYgoVEwguloBmT2flmmRS7DBxaAipY3Dby1iJxCZJyGyoJSCP8NajV7hbKjQ1ZSn2/pK7Weoye7m3JDKhNSZQ9K6Xzg7jPiZr3KUe8dn0ciSHY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258757; c=relaxed/simple; bh=ZgJl7JTJdWh7Jz81s02B+NTCP5MX1PObJN+wOqsO1hg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lwJxi3mfCuwYJ83IN40LDx4mo445n7zz+jS96ioWtJTGXKCRrEwLeEtf6GusmkvzXQ750/i8B9j5NAZyY2VK5Cj3s7+yqgQlwEhZwszJ17kTHWM26QNzLO49UWeTnPIoKEYXRWKPJFISibptatc0vqM/MeYNwbmtsNVkf/2fKMo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vZD61MWO; 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="vZD61MWO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3F231F000CC; Sat, 17 Oct 2026 17:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792258756; bh=KT/PBgO40o20hNtcHr2rJeoyPn8awryk1R47MQB0slU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=vZD61MWOmq6EvPLYrjBUqujR3lkZXdxZdi90VagwZ5KZWKUq9eP0Dz+vo/ix1smun yUJQP8wOuTp3t+K3VhilnmRwZCJ3+6qfpwyK3So/+qgLrdw1WbSNWo+RyoZoPb9Szg 7pkRYjEDOt6fuwxMwTfFEP0nuI/PHOdmLi8Y+bqw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xin Long , Marcelo Ricardo Leitner , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 0990/1674] sctp: disable BH before calling udp_tunnel_xmit_skb() Date: Sat, 17 Oct 2026 17:54:22 +0200 Message-ID: <20261017160456.531600208@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long [ Upstream commit 2cd7e6971fc2787408ceef17906ea152791448cf ] 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: Sasha Levin --- net/sctp/ipv6.c | 10 +++++++--- net/sctp/protocol.c | 2 ++ 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c index 02989e5612df5..4f0647e60dae4 100644 --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -227,6 +227,7 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t) struct ipv6_pinfo *np = inet6_sk(sk); __u8 tclass = np->tclass; __be32 label; + int err; pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n", __func__, skb, skb->len, &fl6->saddr, &fl6->daddr); @@ -263,9 +264,12 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t) skb_set_inner_ipproto(skb, IPPROTO_SCTP); label = ip6_make_flowlabel(sock_net(sk), skb, fl6->flowlabel, true, fl6); - return 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_disable(); + err = 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 err; } /* Returns the dst cache entry for the given source and destination ip diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index ee598e319d0ed..ade01785cb1b5 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -1085,9 +1085,11 @@ static inline int sctp_v4_xmit(struct sk_buff *skb, struct sctp_transport *t) 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((struct 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; } -- 2.53.0