netfilter: nf_flow_table: set default timeout after successful insertion

Set up the default timeout for this new entry otherwise the garbage
collector might quickly remove it right after the flowtable insertion.

Fixes: ac2a6666 ("netfilter: add generic flow table infrastructure")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_flow_table_core.c

@@ -217,7 +217,7 @@ int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow)
 		return err;
 	}
 
-	flow->timeout = (u32)jiffies;
+	flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(flow_offload_add);