net/sock: add WARN_ON(parent->sk) in sock_graft()

sock_graft() unilaterally sets up parent->sk based on the
assumption that the existing parent->sk is null. If this
condition is not true, then the existing parent->sk would
be leaked, so add a WARN_ON() to alert callers who may fall
in this category.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sock.h b/include/net/sock.h
index 48e4d5c..8c85791 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1697,6 +1697,7 @@ static inline void sock_orphan(struct sock *sk)
 
 static inline void sock_graft(struct sock *sk, struct socket *parent)
 {
+       WARN_ON(parent->sk);
        write_lock_bh(&sk->sk_callback_lock);
        sk->sk_wq = parent->wq;
        parent->sk = sk;