netfilter: flowtable: Free block_cb when being deleted

Free block_cb memory when asked to be deleted.

Fixes: 978703f ("netfilter: flowtable: Add API for registering to flow table events")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Oz Shlomo <ozsh@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_flow_table_core.c

@@ -421,10 +421,12 @@ void nf_flow_table_offload_del_cb(struct nf_flowtable *flow_table,
 
 	down_write(&flow_table->flow_block_lock);
 	block_cb = flow_block_cb_lookup(block, cb, cb_priv);
-	if (block_cb)
+	if (block_cb) {
 		list_del(&block_cb->list);
-	else
+		flow_block_cb_free(block_cb);
+	} else {
 		WARN_ON(true);
+	}
 	up_write(&flow_table->flow_block_lock);
 }
 EXPORT_SYMBOL_GPL(nf_flow_table_offload_del_cb);