From fc0adfc8fd18b61b6f7a3f28b429e134d6f3a008 Mon Sep 17 00:00:00 2001 From: Parthasarathy Bhuvaragan Date: Tue, 24 Jan 2017 13:00:45 +0100 Subject: [PATCH] tipc: fix connection refcount error Until now, the generic server framework maintains the connection id's per subscriber in server's conn_idr. At tipc_close_conn, we remove the connection id from the server list, but the connection is valid until we call the refcount cleanup. Hence we have a window where the server allocates the same connection to an new subscriber leading to inconsistent reference count. We have another refcount warning we grab the refcount in tipc_conn_lookup() for connections with flag with CF_CONNECTED not set. This usually occurs at shutdown when the we stop the topology server and withdraw TIPC_CFG_SRV publication thereby triggering a withdraw message to subscribers. In this commit, we: 1. remove the connection from the server list at recount cleanup. 2. grab the refcount for a connection only if CF_CONNECTED is set. Tested-by: John Thompson Acked-by: Ying Xue Acked-by: Jon Maloy Signed-off-by: Parthasarathy Bhuvaragan Signed-off-by: David S. Miller --- net/tipc/server.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/net/tipc/server.c b/net/tipc/server.c index 215849ce453d..2e803601aa99 100644 --- a/net/tipc/server.c +++ b/net/tipc/server.c @@ -91,7 +91,8 @@ static void tipc_sock_release(struct tipc_conn *con); static void tipc_conn_kref_release(struct kref *kref) { struct tipc_conn *con = container_of(kref, struct tipc_conn, kref); - struct sockaddr_tipc *saddr = con->server->saddr; + struct tipc_server *s = con->server; + struct sockaddr_tipc *saddr = s->saddr; struct socket *sock = con->sock; struct sock *sk; @@ -106,6 +107,11 @@ static void tipc_conn_kref_release(struct kref *kref) tipc_sock_release(con); sock_release(sock); con->sock = NULL; + + spin_lock_bh(&s->idr_lock); + idr_remove(&s->conn_idr, con->conid); + s->idr_in_use--; + spin_unlock_bh(&s->idr_lock); } tipc_clean_outqueues(con); @@ -128,8 +134,10 @@ static struct tipc_conn *tipc_conn_lookup(struct tipc_server *s, int conid) spin_lock_bh(&s->idr_lock); con = idr_find(&s->conn_idr, conid); - if (con) + if (con && test_bit(CF_CONNECTED, &con->flags)) conn_get(con); + else + con = NULL; spin_unlock_bh(&s->idr_lock); return con; } @@ -198,15 +206,8 @@ static void tipc_sock_release(struct tipc_conn *con) static void tipc_close_conn(struct tipc_conn *con) { - struct tipc_server *s = con->server; - if (test_and_clear_bit(CF_CONNECTED, &con->flags)) { - spin_lock_bh(&s->idr_lock); - idr_remove(&s->conn_idr, con->conid); - s->idr_in_use--; - spin_unlock_bh(&s->idr_lock); - /* We shouldn't flush pending works as we may be in the * thread. In fact the races with pending rx/tx work structs * are harmless for us here as we have already deleted this -- 2.20.1