1 files changed, 146 insertions, 72 deletions

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index c0d64b4144d4..9346fae5d664 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -63,6 +63,9 @@ static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err);
 
 static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 		     struct sk_buff_head *skbs, u8 event);
+static void l2cap_retrans_timeout(struct work_struct *work);
+static void l2cap_monitor_timeout(struct work_struct *work);
+static void l2cap_ack_timeout(struct work_struct *work);
 
 static inline u8 bdaddr_type(u8 link_type, u8 bdaddr_type)
 {
@@ -113,7 +116,8 @@ static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 }
 
 /* Find channel with given SCID.
- * Returns locked channel. */
+ * Returns a reference locked channel.
+ */
 static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 						 u16 cid)
 {
@@ -121,15 +125,19 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_scid(conn, cid);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
 }
 
 /* Find channel with given DCID.
- * Returns locked channel.
+ * Returns a reference locked channel.
  */
 static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 						 u16 cid)
@@ -138,8 +146,12 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_dcid(conn, cid);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
@@ -164,8 +176,12 @@ static struct l2cap_chan *l2cap_get_chan_by_ident(struct l2cap_conn *conn,
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_ident(conn, ident);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
@@ -457,6 +473,9 @@ struct l2cap_chan *l2cap_chan_create(void)
 	write_unlock(&chan_list_lock);
 
 	INIT_DELAYED_WORK(&chan->chan_timer, l2cap_chan_timeout);
+	INIT_DELAYED_WORK(&chan->retrans_timer, l2cap_retrans_timeout);
+	INIT_DELAYED_WORK(&chan->monitor_timer, l2cap_monitor_timeout);
+	INIT_DELAYED_WORK(&chan->ack_timer, l2cap_ack_timeout);
 
 	chan->state = BT_OPEN;
 
@@ -491,6 +510,16 @@ void l2cap_chan_hold(struct l2cap_chan *c)
 	kref_get(&c->kref);
 }
 
+struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c)
+{
+	BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref));
+
+	if (!kref_get_unless_zero(&c->kref))
+		return NULL;
+
+	return c;
+}
+
 void l2cap_chan_put(struct l2cap_chan *c)
 {
 	BT_DBG("chan %p orig refcnt %d", c, kref_read(&c->kref));
@@ -1781,11 +1810,11 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 						   bdaddr_t *dst,
 						   u8 link_type)
 {
-	struct l2cap_chan *c, *c1 = NULL;
+	struct l2cap_chan *c, *tmp, *c1 = NULL;
 
 	read_lock(&chan_list_lock);
 
-	list_for_each_entry(c, &chan_list, global_l) {
+	list_for_each_entry_safe(c, tmp, &chan_list, global_l) {
 		if (state && c->state != state)
 			continue;
 
@@ -1795,7 +1824,7 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 		if (link_type == LE_LINK && c->src_type == BDADDR_BREDR)
 			continue;
 
-		if (c->psm == psm) {
+		if (c->chan_type != L2CAP_CHAN_FIXED && c->psm == psm) {
 			int src_match, dst_match;
 			int src_any, dst_any;
 
@@ -1803,7 +1832,9 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 			src_match = !bacmp(&c->src, src);
 			dst_match = !bacmp(&c->dst, dst);
 			if (src_match && dst_match) {
-				l2cap_chan_hold(c);
+				if (!l2cap_chan_hold_unless_zero(c))
+					continue;
+
 				read_unlock(&chan_list_lock);
 				return c;
 			}
@@ -1818,7 +1849,7 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 	}
 
 	if (c1)
-		l2cap_chan_hold(c1);
+		c1 = l2cap_chan_hold_unless_zero(c1);
 
 	read_unlock(&chan_list_lock);
 
@@ -2486,14 +2517,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
 		if (IS_ERR(skb))
 			return PTR_ERR(skb);
 
-		/* Channel lock is released before requesting new skb and then
-		 * reacquired thus we need to recheck channel state.
-		 */
-		if (chan->state != BT_CONNECTED) {
-			kfree_skb(skb);
-			return -ENOTCONN;
-		}
-
 		l2cap_do_send(chan, skb);
 		return len;
 	}
@@ -2537,14 +2560,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
 		if (IS_ERR(skb))
 			return PTR_ERR(skb);
 
-		/* Channel lock is released before requesting new skb and then
-		 * reacquired thus we need to recheck channel state.
-		 */
-		if (chan->state != BT_CONNECTED) {
-			kfree_skb(skb);
-			return -ENOTCONN;
-		}
-
 		l2cap_do_send(chan, skb);
 		err = len;
 		break;
@@ -2565,14 +2580,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
 		 */
 		err = l2cap_segment_sdu(chan, &seg_queue, msg, len);
 
-		/* The channel could have been closed while segmenting,
-		 * check that it is still connected.
-		 */
-		if (chan->state != BT_CONNECTED) {
-			__skb_queue_purge(&seg_queue);
-			err = -ENOTCONN;
-		}
-
 		if (err)
 			break;
 
@@ -3129,10 +3136,6 @@ int l2cap_ertm_init(struct l2cap_chan *chan)
 	chan->rx_state = L2CAP_RX_STATE_RECV;
 	chan->tx_state = L2CAP_TX_STATE_XMIT;
 
-	INIT_DELAYED_WORK(&chan->retrans_timer, l2cap_retrans_timeout);
-	INIT_DELAYED_WORK(&chan->monitor_timer, l2cap_monitor_timeout);
-	INIT_DELAYED_WORK(&chan->ack_timer, l2cap_ack_timeout);
-
 	skb_queue_head_init(&chan->srej_q);
 
 	err = l2cap_seq_list_init(&chan->srej_list, chan->tx_win);
@@ -3524,7 +3527,8 @@ done:
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
 					   sizeof(rfc), (unsigned long) &rfc, endptr - ptr);
 
-			if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) {
+			if (remote_efs &&
+			    test_bit(FLAG_EFS_ENABLE, &chan->flags)) {
 				chan->remote_id = efs.id;
 				chan->remote_stype = efs.stype;
 				chan->remote_msdu = le16_to_cpu(efs.msdu);
@@ -4003,6 +4007,10 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 	result = __le16_to_cpu(rsp->result);
 	status = __le16_to_cpu(rsp->status);
 
+	if (result == L2CAP_CR_SUCCESS && (dcid < L2CAP_CID_DYN_START ||
+					   dcid > L2CAP_CID_DYN_END))
+		return -EPROTO;
+
 	BT_DBG("dcid 0x%4.4x scid 0x%4.4x result 0x%2.2x status 0x%2.2x",
 	       dcid, scid, result, status);
 
@@ -4022,12 +4030,23 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 		}
 	}
 
+	chan = l2cap_chan_hold_unless_zero(chan);
+	if (!chan) {
+		err = -EBADSLT;
+		goto unlock;
+	}
+
 	err = 0;
 
 	l2cap_chan_lock(chan);
 
 	switch (result) {
 	case L2CAP_CR_SUCCESS:
+		if (__l2cap_get_chan_by_dcid(conn, dcid)) {
+			err = -EBADSLT;
+			break;
+		}
+
 		l2cap_state_change(chan, BT_CONFIG);
 		chan->ident = 0;
 		chan->dcid = dcid;
@@ -4051,6 +4070,7 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 	}
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 unlock:
 	mutex_unlock(&conn->chan_lock);
@@ -4158,7 +4178,8 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 
 	chan->ident = cmd->ident;
 	l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP, len, rsp);
-	chan->num_conf_rsp++;
+	if (chan->num_conf_rsp < L2CAP_CONF_MAX_CONF_RSP)
+		chan->num_conf_rsp++;
 
 	/* Reset config buffer. */
 	chan->conf_len = 0;
@@ -4204,6 +4225,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 
 unlock:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 	return err;
 }
 
@@ -4316,6 +4338,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 
 done:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 	return err;
 }
 
@@ -4336,33 +4359,29 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn,
 
 	BT_DBG("scid 0x%4.4x dcid 0x%4.4x", scid, dcid);
 
-	mutex_lock(&conn->chan_lock);
-
-	chan = __l2cap_get_chan_by_scid(conn, dcid);
+	chan = l2cap_get_chan_by_scid(conn, dcid);
 	if (!chan) {
-		mutex_unlock(&conn->chan_lock);
 		cmd_reject_invalid_cid(conn, cmd->ident, dcid, scid);
 		return 0;
 	}
 
-	l2cap_chan_hold(chan);
-	l2cap_chan_lock(chan);
-
 	rsp.dcid = cpu_to_le16(chan->scid);
 	rsp.scid = cpu_to_le16(chan->dcid);
 	l2cap_send_cmd(conn, cmd->ident, L2CAP_DISCONN_RSP, sizeof(rsp), &rsp);
 
 	chan->ops->set_shutdown(chan);
 
+	l2cap_chan_unlock(chan);
+	mutex_lock(&conn->chan_lock);
+	l2cap_chan_lock(chan);
 	l2cap_chan_del(chan, ECONNRESET);
+	mutex_unlock(&conn->chan_lock);
 
 	chan->ops->close(chan);
 
 	l2cap_chan_unlock(chan);
 	l2cap_chan_put(chan);
 
-	mutex_unlock(&conn->chan_lock);
-
 	return 0;
 }
 
@@ -4382,33 +4401,28 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
 
 	BT_DBG("dcid 0x%4.4x scid 0x%4.4x", dcid, scid);
 
-	mutex_lock(&conn->chan_lock);
-
-	chan = __l2cap_get_chan_by_scid(conn, scid);
+	chan = l2cap_get_chan_by_scid(conn, scid);
 	if (!chan) {
-		mutex_unlock(&conn->chan_lock);
 		return 0;
 	}
 
-	l2cap_chan_hold(chan);
-	l2cap_chan_lock(chan);
-
 	if (chan->state != BT_DISCONN) {
 		l2cap_chan_unlock(chan);
 		l2cap_chan_put(chan);
-		mutex_unlock(&conn->chan_lock);
 		return 0;
 	}
 
+	l2cap_chan_unlock(chan);
+	mutex_lock(&conn->chan_lock);
+	l2cap_chan_lock(chan);
 	l2cap_chan_del(chan, 0);
+	mutex_unlock(&conn->chan_lock);
 
 	chan->ops->close(chan);
 
 	l2cap_chan_unlock(chan);
 	l2cap_chan_put(chan);
 
-	mutex_unlock(&conn->chan_lock);
-
 	return 0;
 }
 
@@ -5044,6 +5058,7 @@ send_move_response:
 	l2cap_send_move_chan_rsp(chan, result);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5136,6 +5151,7 @@ static void l2cap_move_continue(struct l2cap_conn *conn, u16 icid, u16 result)
 	}
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid,
@@ -5165,6 +5181,7 @@ static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid,
 	l2cap_send_move_chan_cfm(chan, L2CAP_MC_UNCONFIRMED);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static int l2cap_move_channel_rsp(struct l2cap_conn *conn,
@@ -5228,6 +5245,7 @@ static int l2cap_move_channel_confirm(struct l2cap_conn *conn,
 	l2cap_send_move_chan_cfm_rsp(conn, cmd->ident, icid);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5263,6 +5281,7 @@ static inline int l2cap_move_channel_confirm_rsp(struct l2cap_conn *conn,
 	}
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5511,6 +5530,19 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn,
 	BT_DBG("psm 0x%2.2x scid 0x%4.4x mtu %u mps %u", __le16_to_cpu(psm),
 	       scid, mtu, mps);
 
+	/* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
+	 * page 1059:
+	 *
+	 * Valid range: 0x0001-0x00ff
+	 *
+	 * Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges
+	 */
+	if (!psm || __le16_to_cpu(psm) > L2CAP_PSM_LE_DYN_END) {
+		result = L2CAP_CR_BAD_PSM;
+		chan = NULL;
+		goto response;
+	}
+
 	/* Check if we have socket listening on psm */
 	pchan = l2cap_global_chan_by_psm(BT_LISTEN, psm, &conn->hcon->src,
 					 &conn->hcon->dst, LE_LINK);
@@ -5635,12 +5667,11 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn,
 	if (credits > max_credits) {
 		BT_ERR("LE credits overflow");
 		l2cap_send_disconn_req(chan, ECONNRESET);
-		l2cap_chan_unlock(chan);
 
 		/* Return 0 so that we don't trigger an unnecessary
 		 * command reject packet.
 		 */
-		return 0;
+		goto unlock;
 	}
 
 	chan->tx_credits += credits;
@@ -5651,7 +5682,9 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn,
 	if (chan->tx_credits)
 		chan->ops->resume(chan);
 
+unlock:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5672,9 +5705,14 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn,
 	if (!chan)
 		goto done;
 
+	chan = l2cap_chan_hold_unless_zero(chan);
+	if (!chan)
+		goto done;
+
 	l2cap_chan_lock(chan);
 	l2cap_chan_del(chan, ECONNREFUSED);
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 done:
 	mutex_unlock(&conn->chan_lock);
@@ -6213,6 +6251,7 @@ static int l2cap_rx_state_recv(struct l2cap_chan *chan,
 			       struct l2cap_ctrl *control,
 			       struct sk_buff *skb, u8 event)
 {
+	struct l2cap_ctrl local_control;
 	int err = 0;
 	bool skb_in_use = false;
 
@@ -6237,15 +6276,32 @@ static int l2cap_rx_state_recv(struct l2cap_chan *chan,
 			chan->buffer_seq = chan->expected_tx_seq;
 			skb_in_use = true;
 
+			/* l2cap_reassemble_sdu may free skb, hence invalidate
+			 * control, so make a copy in advance to use it after
+			 * l2cap_reassemble_sdu returns and to avoid the race
+			 * condition, for example:
+			 *
+			 * The current thread calls:
+			 *   l2cap_reassemble_sdu
+			 *     chan->ops->recv == l2cap_sock_recv_cb
+			 *       __sock_queue_rcv_skb
+			 * Another thread calls:
+			 *   bt_sock_recvmsg
+			 *     skb_recv_datagram
+			 *     skb_free_datagram
+			 * Then the current thread tries to access control, but
+			 * it was freed by skb_free_datagram.
+			 */
+			local_control = *control;
 			err = l2cap_reassemble_sdu(chan, skb, control);
 			if (err)
 				break;
 
-			if (control->final) {
+			if (local_control.final) {
 				if (!test_and_clear_bit(CONN_REJ_ACT,
 							&chan->conn_state)) {
-					control->final = 0;
-					l2cap_retransmit_all(chan, control);
+					local_control.final = 0;
+					l2cap_retransmit_all(chan, &local_control);
 					l2cap_ertm_send(chan);
 				}
 			}
@@ -6625,11 +6681,27 @@ static int l2cap_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 			   struct sk_buff *skb)
 {
+	/* l2cap_reassemble_sdu may free skb, hence invalidate control, so store
+	 * the txseq field in advance to use it after l2cap_reassemble_sdu
+	 * returns and to avoid the race condition, for example:
+	 *
+	 * The current thread calls:
+	 *   l2cap_reassemble_sdu
+	 *     chan->ops->recv == l2cap_sock_recv_cb
+	 *       __sock_queue_rcv_skb
+	 * Another thread calls:
+	 *   bt_sock_recvmsg
+	 *     skb_recv_datagram
+	 *     skb_free_datagram
+	 * Then the current thread tries to access control, but it was freed by
+	 * skb_free_datagram.
+	 */
+	u16 txseq = control->txseq;
+
 	BT_DBG("chan %p, control %p, skb %p, state %d", chan, control, skb,
 	       chan->rx_state);
 
-	if (l2cap_classify_txseq(chan, control->txseq) ==
-	    L2CAP_TXSEQ_EXPECTED) {
+	if (l2cap_classify_txseq(chan, txseq) == L2CAP_TXSEQ_EXPECTED) {
 		l2cap_pass_to_tx(chan, control);
 
 		BT_DBG("buffer_seq %d->%d", chan->buffer_seq,
@@ -6652,8 +6724,8 @@ static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 		}
 	}
 
-	chan->last_acked_seq = control->txseq;
-	chan->expected_tx_seq = __next_seq(chan, control->txseq);
+	chan->last_acked_seq = txseq;
+	chan->expected_tx_seq = __next_seq(chan, txseq);
 
 	return 0;
 }
@@ -6891,6 +6963,7 @@ static void l2cap_data_channel(struct l2cap_conn *conn, u16 cid,
 				return;
 			}
 
+			l2cap_chan_hold(chan);
 			l2cap_chan_lock(chan);
 		} else {
 			BT_DBG("unknown cid 0x%4.4x", cid);
@@ -6949,6 +7022,7 @@ drop:
 
 done:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm,
@@ -7353,7 +7427,7 @@ static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c,
 		if (src_type != c->src_type)
 			continue;
 
-		l2cap_chan_hold(c);
+		c = l2cap_chan_hold_unless_zero(c);
 		read_unlock(&chan_list_lock);
 		return c;
 	}