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 d452a63d2f4b02a5b382ed9d3737416db284df14..30f5e414018b1a553b92a91736534ebfa20c81a2 100644 (file)
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1902,9 +1902,9 @@ 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);