net/sched: act_ct: remove and free nf_table callbacks

When cleaning up the nf_table in tcf_ct_flow_table_cleanup_work
there is no guarantee that the callback list, added to by
nf_flow_table_offload_add_cb, is empty. This means that it is
possible that the flow_block_cb memory allocated will be lost.

Fix this by iterating the list and freeing the flow_block_cb entries
before freeing the nf_table entry (via freeing ct_ft).

Fixes: 978703f4 ("netfilter: flowtable: Add API for registering to flow table events")
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_ct.c

@@ -322,11 +322,22 @@ static int tcf_ct_flow_table_get(struct tcf_ct_params *params)
 
 static void tcf_ct_flow_table_cleanup_work(struct work_struct *work)
 {
+	struct flow_block_cb *block_cb, *tmp_cb;
 	struct tcf_ct_flow_table *ct_ft;
+	struct flow_block *block;
 
 	ct_ft = container_of(to_rcu_work(work), struct tcf_ct_flow_table,
 			     rwork);
 	nf_flow_table_free(&ct_ft->nf_ft);
+
+	/* Remove any remaining callbacks before cleanup */
+	block = &ct_ft->nf_ft.flow_block;
+	down_write(&ct_ft->nf_ft.flow_block_lock);
+	list_for_each_entry_safe(block_cb, tmp_cb, &block->cb_list, list) {
+		list_del(&block_cb->list);
+		flow_block_cb_free(block_cb);
+	}
+	up_write(&ct_ft->nf_ft.flow_block_lock);
 	kfree(ct_ft);
 
 	module_put(THIS_MODULE);