{"id":2223684,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2223684/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260416013101.221555-2-pablo@netfilter.org/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/1.1/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260416013101.221555-2-pablo@netfilter.org>","date":"2026-04-16T01:30:48","name":"[net,01/14] netfilter: nft_fwd_netdev: use recursion counter in neigh egress path","commit_ref":null,"pull_url":null,"state":"superseded","archived":true,"hash":"00d4880e156e684e260291c466dde58df87616ff","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/1.1/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":{"id":11902,"url":"http://patchwork.ozlabs.org/api/1.1/users/11902/?format=json","username":"strlen","first_name":"Florian","last_name":"Westphal","email":"fw@strlen.de"},"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260416013101.221555-2-pablo@netfilter.org/mbox/","series":[{"id":500063,"url":"http://patchwork.ozlabs.org/api/1.1/series/500063/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=500063","date":"2026-04-16T01:30:47","name":"[net,01/14] netfilter: nft_fwd_netdev: use recursion counter in neigh egress path","version":1,"mbox":"http://patchwork.ozlabs.org/series/500063/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223684/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223684/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=netfilter.org header.i=@netfilter.org\n header.a=rsa-sha256 header.s=2025 header.b=kf/5jmVi;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.105.105.114; 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t=1776303072; c=relaxed/simple;\n\tbh=KtxfLt/oWykY8oTaPQo1JT9xA7ZSb744uumJEXYVKlU=;\n\th=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References:\n\t MIME-Version;\n b=jtD53Ae77UvZ/Hov6IBAZdsTQjbrSXkynfyxPHVwcMcZZIc/0OSjSCcwpDkMZIYVZWcoGtxuV/rLvY71jsPuaBStjcZFGXfXVbqUYCssS9tTYacOba/I397DDq+bdZ1zkq102r3LB7uhfVSDQw01ygX2f3U0rDryWZI7VvdGylw=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=netfilter.org;\n spf=pass smtp.mailfrom=netfilter.org;\n dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org\n header.b=kf/5jmVi; arc=none smtp.client-ip=217.70.190.124","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org;\n\ts=2025; t=1776303068;\n\tbh=oByUcGpenIY1XZsmXVVFXXQyKtnUZiH40rAFcVIDGx0=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=kf/5jmViOF8H2Bf/Dbl4bppaCb/hhbMzZ1uTEw83wBfnwVJkfdiNq9TPmZR1T9L/8\n\t Bj+8Ed/V8HEbeA7sYMyr6aLiSKNNKnkzengOg6MuRcmEzOw8OX2GwUjwfN2IvdnJ1n\n\t GxQfbDfiyYWQYaNz5N5soHQZkqgvNt0CHiGXH6O3d/xxfKtQBJbcC8E1+xND/NSbGp\n\t W+6bKPAqX5hSsdWIjXo4pYPSjOBYHaPb/3cC7PWKFWpvTnMCkcqmxnSgTMoZfI3bB/\n\t Lvc+Wxq9HP0VjenMLuZExNTvkArDCkxRRnW4wZwTS7HSK6zp0dwdwIpp9NBySzC1Y7\n\t vSoqB0DevnOEA==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Cc":"davem@davemloft.net,\n\tnetdev@vger.kernel.org,\n\tkuba@kernel.org,\n\tpabeni@redhat.com,\n\tedumazet@google.com,\n\tfw@strlen.de,\n\thorms@kernel.org","Subject":"[PATCH net 01/14] netfilter: nft_fwd_netdev: use recursion counter in\n neigh egress path","Date":"Thu, 16 Apr 2026 03:30:48 +0200","Message-ID":"<20260416013101.221555-2-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","In-Reply-To":"<20260416013101.221555-1-pablo@netfilter.org>","References":"<20260416013101.221555-1-pablo@netfilter.org>","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"From: Weiming Shi \n\nnft_fwd_neigh can be used in egress chains (NF_NETDEV_EGRESS). When the\nforwarding rule targets the same device or two devices forward to each\nother, neigh_xmit() triggers dev_queue_xmit() which re-enters\nnf_hook_egress(), causing infinite recursion and stack overflow.\n\nMove the nf_get_nf_dup_skb_recursion() accessor and NF_RECURSION_LIMIT\nto the shared header nf_dup_netdev.h as a static inline, so that\nnft_fwd_netdev can use the recursion counter directly without exported\nfunction call overhead. Guard neigh_xmit() with the same recursion\nlimit already used in nf_do_netdev_egress().\n\nFixes: f87b9464d152 (\"netfilter: nft_fwd_netdev: Support egress hook\")\nReported-by: Xiang Mei \nSigned-off-by: Weiming Shi \nSigned-off-by: Pablo Neira Ayuso \n---\n include/net/netfilter/nf_dup_netdev.h | 13 +++++++++++++\n net/netfilter/nf_dup_netdev.c | 16 ----------------\n net/netfilter/nft_fwd_netdev.c | 7 +++++++\n 3 files changed, 20 insertions(+), 16 deletions(-)","diff":"diff --git a/include/net/netfilter/nf_dup_netdev.h b/include/net/netfilter/nf_dup_netdev.h\nindex b175d271aec9..609bcf422a9b 100644\n--- a/include/net/netfilter/nf_dup_netdev.h\n+++ b/include/net/netfilter/nf_dup_netdev.h\n@@ -3,10 +3,23 @@\n #define _NF_DUP_NETDEV_H_\n \n #include \n+#include \n+#include \n \n void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif);\n void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif);\n \n+#define NF_RECURSION_LIMIT\t2\n+\n+static inline u8 *nf_get_nf_dup_skb_recursion(void)\n+{\n+#ifndef CONFIG_PREEMPT_RT\n+\treturn this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion);\n+#else\n+\treturn ¤t->net_xmit.nf_dup_skb_recursion;\n+#endif\n+}\n+\n struct nft_offload_ctx;\n struct nft_flow_rule;\n \ndiff --git a/net/netfilter/nf_dup_netdev.c b/net/netfilter/nf_dup_netdev.c\nindex fab8b9011098..a958a1b0c5be 100644\n--- a/net/netfilter/nf_dup_netdev.c\n+++ b/net/netfilter/nf_dup_netdev.c\n@@ -13,22 +13,6 @@\n #include \n #include \n \n-#define NF_RECURSION_LIMIT\t2\n-\n-#ifndef CONFIG_PREEMPT_RT\n-static u8 *nf_get_nf_dup_skb_recursion(void)\n-{\n-\treturn this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion);\n-}\n-#else\n-\n-static u8 *nf_get_nf_dup_skb_recursion(void)\n-{\n-\treturn ¤t->net_xmit.nf_dup_skb_recursion;\n-}\n-\n-#endif\n-\n static void nf_do_netdev_egress(struct sk_buff *skb, struct net_device *dev,\n \t\t\t\tenum nf_dev_hooks hook)\n {\ndiff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c\nindex 152a9fb4d23a..492bb599a499 100644\n--- a/net/netfilter/nft_fwd_netdev.c\n+++ b/net/netfilter/nft_fwd_netdev.c\n@@ -141,13 +141,20 @@ static void nft_fwd_neigh_eval(const struct nft_expr *expr,\n \t\tgoto out;\n \t}\n \n+\tif (*nf_get_nf_dup_skb_recursion() > NF_RECURSION_LIMIT) {\n+\t\tverdict = NF_DROP;\n+\t\tgoto out;\n+\t}\n+\n \tdev = dev_get_by_index_rcu(nft_net(pkt), oif);\n \tif (dev == NULL)\n \t\treturn;\n \n \tskb->dev = dev;\n \tskb_clear_tstamp(skb);\n+\t(*nf_get_nf_dup_skb_recursion())++;\n \tneigh_xmit(neigh_table, dev, addr, skb);\n+\t(*nf_get_nf_dup_skb_recursion())--;\n out:\n \tregs->verdict.code = verdict;\n }\n","prefixes":["net","01/14"]}