Bluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled

HCI_UART_SENDING bit in tx_state means write_work is pending and blocks
queueing it again.  Currently this bit is not cleared when canceling the
work in hci_uart_close(), which blocks future writes when device is
reopened later if write_work was pending.

Fix by clearing HCI_UART_SENDING when canceling the work.

Also make clearing of tx_skb safe by using disable_work_sync +
enable_work instead of just cancel_work_sync.  hci_uart_flush() purges
the proto tx queue so we can cancel the pending write_work there,
instead of doing it just in hci_uart_close().  Re-enable and possibly
requeue the work after queue flush.

Fixes: c1bb9336ae6b ("Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths")
Link: https://lore.kernel.org/linux-bluetooth/07e0a28650773abec711ee492fdb1bf5d21a6c98.camel@iki.fi/
Cc: stable@vger.kernel.org
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 47f4902b40b47dd31eacb62a11edeceb9b47d8f8..2ad42c3bbaac78ed74cbf1c7cc4200876bb444c1 100644 (file)
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -239,6 +239,8 @@ static int hci_uart_flush(struct hci_dev *hdev)
 
        BT_DBG("hdev %p tty %p", hdev, tty);
 
+       disable_work_sync(&hu->write_work);
+
        if (hu->tx_skb) {
                kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
        }
@@ -254,6 +256,14 @@ static int hci_uart_flush(struct hci_dev *hdev)
 
        percpu_up_read(&hu->proto_lock);
 
+       /* Resume TX. Also reschedule in case work was queued concurrently;
+        * this may schedule write_work although there's nothing to do.
+        */
+       enable_work(&hu->write_work);
+       clear_bit(HCI_UART_SENDING, &hu->tx_state);
+       if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
+               hci_uart_tx_wakeup(hu);
+
        return 0;
 }
 
@@ -271,12 +281,8 @@ static int hci_uart_open(struct hci_dev *hdev)
 /* Close device */
 static int hci_uart_close(struct hci_dev *hdev)
 {
-       struct hci_uart *hu = hci_get_drvdata(hdev);
-
        BT_DBG("hdev %p", hdev);
 
-       cancel_work_sync(&hu->write_work);
-
        hci_uart_flush(hdev);
        hdev->flush = NULL;
        return 0;