Bluetooth: hci_event: Fix using rcu_read_(un)lock while iterating

[ Upstream commit 581dd2d ]

The usage of rcu_read_(un)lock while inside list_for_each_entry_rcu is
not safe since for the most part entries fetched this way shall be
treated as rcu_dereference:

	Note that the value returned by rcu_dereference() is valid
	only within the enclosing RCU read-side critical section [1]_.
	For example, the following is **not** legal::

		rcu_read_lock();
		p = rcu_dereference(head.next);
		rcu_read_unlock();
		x = p->address;	/* BUG!!! */
		rcu_read_lock();
		y = p->data;	/* BUG!!! */
		rcu_read_unlock();

Fixes: a0bfde1 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Signed-off-by: Luiz Augusto von Dentz <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: Vudentz

net/bluetooth/hci_event.c

@@ -6821,38 +6821,27 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 		return;
 
 	hci_dev_lock(hdev);
-	rcu_read_lock();
 
 	/* Connect all BISes that are bound to the BIG */
-	list_for_each_entry_rcu(conn, &hdev->conn_hash.list, list) {
-		if (bacmp(&conn->dst, BDADDR_ANY) ||
-		    conn->type != ISO_LINK ||
-		    conn->iso_qos.bcast.big != ev->handle)
+	while ((conn = hci_conn_hash_lookup_big_state(hdev, ev->handle,
+						      BT_BOUND))) {
+		if (ev->status) {
+			hci_connect_cfm(conn, ev->status);
+			hci_conn_del(conn);
 			continue;
+		}
 
 		if (hci_conn_set_handle(conn,
 					__le16_to_cpu(ev->bis_handle[i++])))
 			continue;
 
-		if (!ev->status) {
-			conn->state = BT_CONNECTED;
-			set_bit(HCI_CONN_BIG_CREATED, &conn->flags);
-			rcu_read_unlock();
-			hci_debugfs_create_conn(conn);
-			hci_conn_add_sysfs(conn);
-			hci_iso_setup_path(conn);
-			rcu_read_lock();
-			continue;
-		}
-
-		hci_connect_cfm(conn, ev->status);
-		rcu_read_unlock();
-		hci_conn_del(conn);
-		rcu_read_lock();
+		conn->state = BT_CONNECTED;
+		set_bit(HCI_CONN_BIG_CREATED, &conn->flags);
+		hci_debugfs_create_conn(conn);
+		hci_conn_add_sysfs(conn);
+		hci_iso_setup_path(conn);
 	}
 
-	rcu_read_unlock();
-
 	if (!ev->status && !i)
 		/* If no BISes have been connected for the BIG,
 		 * terminate. This is in case all bound connections