diff options
| -rw-r--r-- | net/bluetooth/af_bluetooth.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index a374fd27b5e1..42d0997e2fbb 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -167,6 +167,9 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk) } EXPORT_SYMBOL(bt_accept_enqueue); +/* Calling function must hold the sk lock. + * bt_sk(sk)->parent must be non-NULL meaning sk is in the parent list. + */ void bt_accept_unlink(struct sock *sk) { BT_DBG("sk %p state %d", sk, sk->sk_state); @@ -185,11 +188,32 @@ struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock) BT_DBG("parent %p", parent); +restart: list_for_each_entry_safe(s, n, &bt_sk(parent)->accept_q, accept_q) { sk = (struct sock *)s; + /* Prevent early freeing of sk due to unlink and sock_kill */ + sock_hold(sk); lock_sock(sk); + /* Check sk has not already been unlinked via + * bt_accept_unlink() due to serialisation caused by sk locking + */ + if (!bt_sk(sk)->parent) { + BT_DBG("sk %p, already unlinked", sk); + release_sock(sk); + sock_put(sk); + + /* Restart the loop as sk is no longer in the list + * and also avoid a potential infinite loop because + * list_for_each_entry_safe() is not thread safe. + */ + goto restart; + } + + /* sk is safely in the parent list so reduce reference count */ + sock_put(sk); + /* FIXME: Is this check still needed */ if (sk->sk_state == BT_CLOSED) { bt_accept_unlink(sk); |