1 files changed, 28 insertions, 7 deletions

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index bd3c021932be..6c127f4ac3a2 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1038,7 +1038,7 @@ done:
 }
 
 /* Kill socket (only if zapped and orphan)
- * Must be called on unlocked socket.
+ * Must be called on unlocked socket, with l2cap channel lock.
  */
 static void l2cap_sock_kill(struct sock *sk)
 {
@@ -1189,6 +1189,7 @@ static int l2cap_sock_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
 	int err;
+	struct l2cap_chan *chan;
 
 	BT_DBG("sock %pK, sk %pK", sock, sk);
 
@@ -1198,9 +1199,17 @@ static int l2cap_sock_release(struct socket *sock)
 	bt_sock_unlink(&l2cap_sk_list, sk);
 
 	err = l2cap_sock_shutdown(sock, 2);
+	chan = l2cap_pi(sk)->chan;
+
+	l2cap_chan_hold(chan);
+	l2cap_chan_lock(chan);
 
 	sock_orphan(sk);
 	l2cap_sock_kill(sk);
+
+	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
+
 	return err;
 }
 
@@ -1218,12 +1227,15 @@ static void l2cap_sock_cleanup_listen(struct sock *parent)
 		BT_DBG("child chan %pK state %s", chan,
 		       state_to_string(chan->state));
 
+		l2cap_chan_hold(chan);
 		l2cap_chan_lock(chan);
+
 		__clear_chan_timer(chan);
 		l2cap_chan_close(chan, ECONNRESET);
-		l2cap_chan_unlock(chan);
-
 		l2cap_sock_kill(sk);
+
+		l2cap_chan_unlock(chan);
+		l2cap_chan_put(chan);
 	}
 }
 
@@ -1297,6 +1309,9 @@ static void l2cap_sock_close_cb(struct l2cap_chan *chan)
 {
 	struct sock *sk = chan->data;
 
+	if (!sk)
+		return;
+
 	l2cap_sock_kill(sk);
 }
 
@@ -1305,6 +1320,9 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
 	struct sock *sk = chan->data;
 	struct sock *parent;
 
+	if (!sk)
+		return;
+
 	BT_DBG("chan %pK state %s", chan, state_to_string(chan->state));
 
 	/* This callback can be called both for server (BT_LISTEN)
@@ -1318,8 +1336,6 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
 
 	parent = bt_sk(sk)->parent;
 
-	sock_set_flag(sk, SOCK_ZAPPED);
-
 	switch (chan->state) {
 	case BT_OPEN:
 	case BT_BOUND:
@@ -1346,8 +1362,11 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
 
 		break;
 	}
-
 	release_sock(sk);
+
+	/* Only zap after cleanup to avoid use after free race */
+	sock_set_flag(sk, SOCK_ZAPPED);
+
 }
 
 static void l2cap_sock_state_change_cb(struct l2cap_chan *chan, int state,
@@ -1473,8 +1492,10 @@ static void l2cap_sock_destruct(struct sock *sk)
 {
 	BT_DBG("sk %pK", sk);
 
-	if (l2cap_pi(sk)->chan)
+	if (l2cap_pi(sk)->chan) {
+		l2cap_pi(sk)->chan->data = NULL;
 		l2cap_chan_put(l2cap_pi(sk)->chan);
+	}
 
 	if (l2cap_pi(sk)->rx_busy_skb) {
 		kfree_skb(l2cap_pi(sk)->rx_busy_skb);