USB: serial/keyspan_pda, fix potential tty NULL dereferences

Make sure that we check the return value of tty_port_tty_get.
Sometimes it may return NULL and we later dereference that.

There are several places to check. For easier handling,
tty_port_tty_get is moved directly to the palce where needed in
keyspan_pda_rx_interrupt.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 554a8693a463aabda0f4b514cad5574ab623b0be..7b690f3282a2284585b8a345b8d1260c4f776834 100644 (file)
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -173,7 +173,8 @@ static void keyspan_pda_wakeup_write(struct work_struct *work)
                container_of(work, struct keyspan_pda_private, wakeup_work);
        struct usb_serial_port *port = priv->port;
        struct tty_struct *tty = tty_port_tty_get(&port->port);
-       tty_wakeup(tty);
+       if (tty)
+               tty_wakeup(tty);
        tty_kref_put(tty);
 }
 
@@ -206,7 +207,7 @@ static void keyspan_pda_request_unthrottle(struct work_struct *work)
 static void keyspan_pda_rx_interrupt(struct urb *urb)
 {
        struct usb_serial_port *port = urb->context;
-       struct tty_struct *tty = tty_port_tty_get(&port->port);
+       struct tty_struct *tty;
        unsigned char *data = urb->transfer_buffer;
        int retval;
        int status = urb->status;
@@ -223,7 +224,7 @@ static void keyspan_pda_rx_interrupt(struct urb *urb)
                /* this urb is terminated, clean up */
                dbg("%s - urb shutting down with status: %d",
                    __func__, status);
-               goto out;
+               return;
        default:
                dbg("%s - nonzero urb status received: %d",
                    __func__, status);
@@ -233,12 +234,14 @@ static void keyspan_pda_rx_interrupt(struct urb *urb)
        /* see if the message is data or a status interrupt */
        switch (data[0]) {
        case 0:
-               /* rest of message is rx data */
-               if (urb->actual_length) {
+               tty = tty_port_tty_get(&port->port);
+                /* rest of message is rx data */
+               if (tty && urb->actual_length) {
                        tty_insert_flip_string(tty, data + 1,
                                                urb->actual_length - 1);
                        tty_flip_buffer_push(tty);
                }
+               tty_kref_put(tty);
                break;
        case 1:
                /* status interrupt */
@@ -265,8 +268,6 @@ exit:
                dev_err(&port->dev,
                        "%s - usb_submit_urb failed with result %d",
                        __func__, retval);
-out:
-       tty_kref_put(tty);                   
 }