[PATCH 3.16 127/132] Bluetooth: hci_ldisc: Fix null pointer derefence in case of early data

[Ben Hutchings]

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Loic Poulain <loic.poul...@intel.com>

commit 84cb3df02aea4b00405521e67c4c67c2d525c364 upstream.

HCI_UART_PROTO_SET flag is set before hci_uart_set_proto call. If we
receive data from tty layer during this procedure, proto pointer may
not be assigned yet, leading to null pointer dereference in rx method
hci_uart_tty_receive.

This patch fixes this issue by introducing HCI_UART_PROTO_READY flag in
order to avoid any proto operation before proto opening and assignment.

Signed-off-by: Loic Poulain <loic.poul...@intel.com>
Signed-off-by: Marcel Holtmann <mar...@holtmann.org>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/bluetooth/hci_ldisc.c | 11 +++++++----
 drivers/bluetooth/hci_uart.h  |  1 +
 2 files changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -225,7 +225,7 @@ static int hci_uart_flush(struct hci_dev
        tty_ldisc_flush(tty);
        tty_driver_flush_buffer(tty);
 
-       if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
+       if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
                hu->proto->flush(hu);
 
        return 0;
@@ -342,7 +342,7 @@ static void hci_uart_tty_close(struct tt
 
        cancel_work_sync(&hu->write_work);
 
-       if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) {
+       if (test_and_clear_bit(HCI_UART_PROTO_READY, &hu->flags)) {
                if (hdev) {
                        if (test_bit(HCI_UART_REGISTERED, &hu->flags))
                                hci_unregister_dev(hdev);
@@ -350,6 +350,7 @@ static void hci_uart_tty_close(struct tt
                }
                hu->proto->close(hu);
        }
+       clear_bit(HCI_UART_PROTO_SET, &hu->flags);
 
        kfree(hu);
 }
@@ -376,7 +377,7 @@ static void hci_uart_tty_wakeup(struct t
        if (tty != hu->tty)
                return;
 
-       if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
+       if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
                hci_uart_tx_wakeup(hu);
 }
 
@@ -399,7 +400,7 @@ static void hci_uart_tty_receive(struct
        if (!hu || tty != hu->tty)
                return;
 
-       if (!test_bit(HCI_UART_PROTO_SET, &hu->flags))
+       if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
                return;
 
        spin_lock(&hu->rx_lock);
@@ -476,9 +477,11 @@ static int hci_uart_set_proto(struct hci
                return err;
 
        hu->proto = p;
+       set_bit(HCI_UART_PROTO_READY, &hu->flags);
 
        err = hci_uart_register_dev(hu);
        if (err) {
+               clear_bit(HCI_UART_PROTO_READY, &hu->flags);
                p->close(hu);
                return err;
        }
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -81,6 +81,7 @@ struct hci_uart {
 /* HCI_UART proto flag bits */
 #define HCI_UART_PROTO_SET     0
 #define HCI_UART_REGISTERED    1
+#define HCI_UART_PROTO_READY   2
 
 /* TX states  */
 #define HCI_UART_SENDING       1