net: convert sock.sk_refcnt from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

This patch uses refcount_inc_not_zero() instead of
atomic_inc_not_zero_hint() due to absense of a _hint()
version of refcount API. If the hint() version must
be used, we might need to revisit API.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 1b92b72..101e359 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2313,7 +2313,7 @@ static void tipc_sk_remove(struct tipc_sock *tsk)
 	struct tipc_net *tn = net_generic(sock_net(sk), tipc_net_id);
 
 	if (!rhashtable_remove_fast(&tn->sk_rht, &tsk->node, tsk_rht_params)) {
-		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
+		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
 		__sock_put(sk);
 	}
 }