Re: [PATCH 2/2] rxrpc: Fix rxrpc_local leak in rxrpc_lookup_peer()

From: Eiichi Tsukata <redacted>

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: 9ebeddef58c4 ("rxrpc: rxrpc_peer needs to hold a ref on the rxrpc_local record")
Signed-off-by: Eiichi Tsukata <redacted>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: 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/ (local) # v1
---

 net/rxrpc/peer_object.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index 68396d052052..0298fe2ad6d3 100644
--- a/net/rxrpc/peer_object.c
+++ b/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);
        }
 }