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

[ Upstream commit 5ea7b72d4fac2fdbc0425cd8f2ea33abe95235b2 ]

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: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://lore.kernel.org/r/ZiYvzQN/Ry5oeFQW@v4bel-B760M-AORUS-ELITE-AX
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 60dd6f32d520eca334a61614d0f4d1591fb23bf1..85a338b6817809f0a61406bbf929ccf646755be1 100644 (file)
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1913,9 +1913,9 @@ 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);