rxrpc: Fix rxrpc_local leak in rxrpc_lookup_peer()

Need to call rxrpc_put_local() for peer candidate before kfree() as it
holds a ref to rxrpc_local.

[DH: v2: Changed to abstract the peer freeing code out into a function]

Fixes: 9ebeddef ("rxrpc: rxrpc_peer needs to hold a ref on the rxrpc_local record")
Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/all/20211121041608.133740-2-eiichi.tsukata@nutanix.com/ # v1

net/rxrpc/peer_object.c

@@ -299,6 +299,12 @@ static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_sock *rx,
 	return peer;
 }
 
+static void rxrpc_free_peer(struct rxrpc_peer *peer)
+{
+	rxrpc_put_local(peer->local);
+	kfree_rcu(peer, rcu);
+}
+
 /*
  * Set up a new incoming peer.  There shouldn't be any other matching peers
  * since we've already done a search in the list from the non-reentrant context
@@ -365,7 +371,7 @@ struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_sock *rx,
 		spin_unlock_bh(&rxnet->peer_hash_lock);
 
 		if (peer)
-			kfree(candidate);
+			rxrpc_free_peer(candidate);
 		else
 			peer = candidate;
 	}
@@ -420,8 +426,7 @@ static void __rxrpc_put_peer(struct rxrpc_peer *peer)
 	list_del_init(&peer->keepalive_link);
 	spin_unlock_bh(&rxnet->peer_hash_lock);
 
-	rxrpc_put_local(peer->local);
-	kfree_rcu(peer, rcu);
+	rxrpc_free_peer(peer);
 }
 
 /*
@@ -457,8 +462,7 @@ void rxrpc_put_peer_locked(struct rxrpc_peer *peer)
 	if (n == 0) {
 		hash_del_rcu(&peer->hash_link);
 		list_del_init(&peer->keepalive_link);
-		rxrpc_put_local(peer->local);
-		kfree_rcu(peer, rcu);
+		rxrpc_free_peer(peer);
 	}
 }