net: openvswitch: Fix Use-After-Free in ovs_ct_exit

jira LE-1907
cve CVE-2024-27395
Rebuild_History Non-Buildable kernel-4.18.0-553.16.1.el8_10
commit-author Hyunwoo Kim <[email protected]>
commit 5ea7b72

Since kfree_rcu, which is called in the hlist_for_each_entry_rcu traversal
of ovs_ct_limit_exit, is not part of the RCU read critical section, it
is possible that the RCU grace period will pass during the traversal and
the key will be free.

To prevent this, it should be changed to hlist_for_each_entry_safe.

Fixes: 11efd5c ("openvswitch: Support conntrack zone limit")
	Signed-off-by: Hyunwoo Kim <[email protected]>
	Reviewed-by: Eric Dumazet <[email protected]>
	Reviewed-by: Aaron Conole <[email protected]>
Link: https://lore.kernel.org/r/ZiYvzQN/Ry5oeFQW@v4bel-B760M-AORUS-ELITE-AX
	Signed-off-by: Jakub Kicinski <[email protected]>
(cherry picked from commit 5ea7b72)
	Signed-off-by: Jonathan Maple <[email protected]>

Author: PlaidCat

net/openvswitch/conntrack.c

@@ -1916,9 +1916,9 @@ static void ovs_ct_limit_exit(struct net *net, struct ovs_net *ovs_net)
 	for (i = 0; i < CT_LIMIT_HASH_BUCKETS; ++i) {
 		struct hlist_head *head = &info->limits[i];
 		struct ovs_ct_limit *ct_limit;
+		struct hlist_node *next;
 
-		hlist_for_each_entry_rcu(ct_limit, head, hlist_node,
-					 lockdep_ovsl_is_held())
+		hlist_for_each_entry_safe(ct_limit, next, head, hlist_node)
 			kfree_rcu(ct_limit, rcu);
 	}
 	kfree(info->limits);