netfilter: nf_conncount: callers must hold rcu read lock

[ Upstream commit 64d7d5a ]

rcu_derefence_raw() should not have been used here, it concealed this bug.
Its used because struct rb_node lacks __rcu annotated pointers, so plain
rcu_derefence causes sparse warnings.

The major tradeoff is that rcu_derefence_raw() doesn't warn when the caller
isn't in a rcu read section.

Extend the rcu read lock scope accordingly and cause sparse warnings,
those warnings are the lesser evil.

Fixes: 11efd5c ("openvswitch: Support conntrack zone limit")
Closes: https://sashiko.dev/#/patchset/20260603230610.7900-1-fw%40strlen.de
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Florian Westphal

net/netfilter/nf_conncount.c

@@ -499,17 +499,17 @@ count_tree(struct net *net,
 	hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
 	root = &data->root[hash];
 
-	parent = rcu_dereference_raw(root->rb_node);
+	parent = rcu_dereference(root->rb_node);
 	while (parent) {
 		int diff;
 
 		rbconn = rb_entry(parent, struct nf_conncount_rb, node);
 
 		diff = key_diff(key, rbconn->key, data->keylen);
 		if (diff < 0) {
-			parent = rcu_dereference_raw(parent->rb_left);
+			parent = rcu_dereference(parent->rb_left);
 		} else if (diff > 0) {
-			parent = rcu_dereference_raw(parent->rb_right);
+			parent = rcu_dereference(parent->rb_right);
 		} else {
 			int ret;
 

net/openvswitch/conntrack.c

@@ -1774,10 +1774,10 @@ static int ovs_ct_limit_get_zone_limit(struct net *net,
 		} else {
 			rcu_read_lock();
 			limit = ct_limit_get(info, zone);
-			rcu_read_unlock();
 
 			err = __ovs_ct_limit_get_zone_limit(
 				net, info->data, zone, limit, reply);
+			rcu_read_unlock();
 			if (err)
 				return err;
 		}