[PATCH 3.4 22/43] USB: usb_wwan: fix potential NULL-deref at resume

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <jhovold@gmail.com>

commit 9096f1fbba916c2e052651e9de82fcfb98d4bea7 upstream.

The interrupt urb was submitted unconditionally at resume, something
which could lead to a NULL-pointer dereference in the urb completion
handler as resume may be called after the port and port data is gone.

Fix this by making sure the interrupt urb is only submitted and active
when the port is open.

Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the
option driver")

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/usb_wwan.c |   42 ++++++++++++++++++++----------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -408,6 +408,14 @@ int usb_wwan_open(struct tty_struct *tty
 
 	dbg("%s", __func__);
 
+	if (port->interrupt_in_urb) {
+		err = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
+		if (err) {
+			dev_dbg(&port->dev, "%s: submit int urb failed: %d\n",
+				__func__, err);
+		}
+	}
+
 	/* Start reading from the IN endpoint */
 	for (i = 0; i < N_IN_URB; i++) {
 		urb = portdata->in_urbs[i];
@@ -476,6 +484,7 @@ void usb_wwan_close(struct usb_serial_po
 			usb_kill_urb(portdata->in_urbs[i]);
 		for (i = 0; i < N_OUT_URB; i++)
 			usb_kill_urb(portdata->out_urbs[i]);
+		usb_kill_urb(port->interrupt_in_urb);
 		/* balancing - important as an error cannot be handled*/
 		usb_autopm_get_interface_no_resume(serial->interface);
 		serial->interface->needs_remote_wakeup = 0;
@@ -551,7 +560,7 @@ static void usb_wwan_setup_urbs(struct u
 
 int usb_wwan_startup(struct usb_serial *serial)
 {
-	int i, j, err;
+	int i, j;
 	struct usb_serial_port *port;
 	struct usb_wwan_port_private *portdata;
 	u8 *buffer;
@@ -584,12 +593,6 @@ int usb_wwan_startup(struct usb_serial *
 		}
 
 		usb_set_serial_port_data(port, portdata);
-
-		if (!port->interrupt_in_urb)
-			continue;
-		err = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
-		if (err)
-			dbg("%s: submit irq_in urb failed %d", __func__, err);
 	}
 	usb_wwan_setup_urbs(serial);
 	return 0;
@@ -723,21 +726,6 @@ int usb_wwan_resume(struct usb_serial *s
 	int err = 0;
 
 	dbg("%s entered", __func__);
-	/* get the interrupt URBs resubmitted unconditionally */
-	for (i = 0; i < serial->num_ports; i++) {
-		port = serial->port[i];
-		if (!port->interrupt_in_urb) {
-			dbg("%s: No interrupt URB for port %d", __func__, i);
-			continue;
-		}
-		err = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
-		dbg("Submitted interrupt URB for port %d (result %d)", i, err);
-		if (err < 0) {
-			err("%s: Error %d for interrupt URB of port%d",
-			    __func__, err, i);
-			goto err_out;
-		}
-	}
 
 	spin_lock_irq(&intfdata->susp_lock);
 	for (i = 0; i < serial->num_ports; i++) {
@@ -749,6 +737,16 @@ int usb_wwan_resume(struct usb_serial *s
 		if (!portdata || !portdata->opened)
 			continue;
 
+		if (port->interrupt_in_urb) {
+			err = usb_submit_urb(port->interrupt_in_urb,
+					GFP_ATOMIC);
+			if (err) {
+				dev_err(&port->dev,
+					"%s: submit int urb failed: %d\n",
+					__func__, err);
+			}
+		}
+
 		for (j = 0; j < N_IN_URB; j++) {
 			urb = portdata->in_urbs[j];
 			err = usb_submit_urb(urb, GFP_ATOMIC);