1 files changed, 35 insertions, 4 deletions

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 511a1da6ca97..13d070e7738d 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -179,9 +179,17 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr,
 	struct l2cap_chan *chan = l2cap_pi(sk)->chan;
 	struct sockaddr_l2 la;
 	int len, err = 0;
+	bool zapped;
 
 	BT_DBG("sk %p", sk);
 
+	lock_sock(sk);
+	zapped = sock_flag(sk, SOCK_ZAPPED);
+	release_sock(sk);
+
+	if (zapped)
+		return -EINVAL;
+
 	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
 	    addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;
@@ -1321,6 +1329,9 @@ static void l2cap_sock_close_cb(struct l2cap_chan *chan)
 {
 	struct sock *sk = chan->data;
 
+	if (!sk)
+		return;
+
 	l2cap_sock_kill(sk);
 }
 
@@ -1329,6 +1340,9 @@ 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 %p state %s", chan, state_to_string(chan->state));
 
 	/* This callback can be called both for server (BT_LISTEN)
@@ -1342,8 +1356,6 @@ 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:
@@ -1370,8 +1382,11 @@ 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,
@@ -1477,6 +1492,19 @@ static void l2cap_sock_suspend_cb(struct l2cap_chan *chan)
 	sk->sk_state_change(sk);
 }
 
+static int l2cap_sock_filter(struct l2cap_chan *chan, struct sk_buff *skb)
+{
+	struct sock *sk = chan->data;
+
+	switch (chan->mode) {
+	case L2CAP_MODE_ERTM:
+	case L2CAP_MODE_STREAMING:
+		return sk_filter(sk, skb);
+	}
+
+	return 0;
+}
+
 static const struct l2cap_ops l2cap_chan_ops = {
 	.name			= "L2CAP Socket Interface",
 	.new_connection		= l2cap_sock_new_connection_cb,
@@ -1491,14 +1519,17 @@ static const struct l2cap_ops l2cap_chan_ops = {
 	.set_shutdown		= l2cap_sock_set_shutdown_cb,
 	.get_sndtimeo		= l2cap_sock_get_sndtimeo_cb,
 	.alloc_skb		= l2cap_sock_alloc_skb_cb,
+	.filter			= l2cap_sock_filter,
 };
 
 static void l2cap_sock_destruct(struct sock *sk)
 {
 	BT_DBG("sk %p", 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);