netdev - [PATCH net 1/4] netfilter: nf_conncount: fix leaked ct in error paths

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Message-ID: <20251210110754.22620-2-fw@strlen.de>
Date: Wed, 10 Dec 2025 12:07:51 +0100
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	<netfilter-devel@...r.kernel.org>,
	pablo@...filter.org
Subject: [PATCH net 1/4] netfilter: nf_conncount: fix leaked ct in error paths

From: Fernando Fernandez Mancera <fmancera@...e.de>

There are some situations where ct might be leaked as error paths are
skipping the refcounted check and return immediately. In order to solve
it make sure that the check is always called.

Fixes: be102eb6a0e7 ("netfilter: nf_conncount: rework API to use sk_buff directly")
Signed-off-by: Fernando Fernandez Mancera <fmancera@...e.de>
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nf_conncount.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
index f1be4dd5cf85..3654f1e8976c 100644
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -172,14 +172,14 @@ static int __nf_conncount_add(struct net *net,
 	struct nf_conn *found_ct;
 	unsigned int collect = 0;
 	bool refcounted = false;
+	int err = 0;
 
 	if (!get_ct_or_tuple_from_skb(net, skb, l3num, &ct, &tuple, &zone, &refcounted))
 		return -ENOENT;
 
 	if (ct && nf_ct_is_confirmed(ct)) {
-		if (refcounted)
-			nf_ct_put(ct);
-		return -EEXIST;
+		err = -EEXIST;
+		goto out_put;
 	}
 
 	if ((u32)jiffies == list->last_gc)
@@ -231,12 +231,16 @@ static int __nf_conncount_add(struct net *net,
 	}
 
 add_new_node:
-	if (WARN_ON_ONCE(list->count > INT_MAX))
-		return -EOVERFLOW;
+	if (WARN_ON_ONCE(list->count > INT_MAX)) {
+		err = -EOVERFLOW;
+		goto out_put;
+	}
 
 	conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
-	if (conn == NULL)
-		return -ENOMEM;
+	if (conn == NULL) {
+		err = -ENOMEM;
+		goto out_put;
+	}
 
 	conn->tuple = tuple;
 	conn->zone = *zone;
@@ -249,7 +253,7 @@ static int __nf_conncount_add(struct net *net,
 out_put:
 	if (refcounted)
 		nf_ct_put(ct);
-	return 0;
+	return err;
 }
 
 int nf_conncount_add_skb(struct net *net,
@@ -456,11 +460,10 @@ insert_tree(struct net *net,
 
 		rb_link_node_rcu(&rbconn->node, parent, rbnode);
 		rb_insert_color(&rbconn->node, root);
-
-		if (refcounted)
-			nf_ct_put(ct);
 	}
 out_unlock:
+	if (refcounted)
+		nf_ct_put(ct);
 	spin_unlock_bh(&nf_conncount_locks[hash]);
 	return count;
 }
-- 
2.51.2