USB: serial: io_ti: fix another NULL-deref at open

In case a device is left in "boot-mode" we must not register any port
devices in order to avoid a NULL-pointer dereference on open due to
missing endpoints. This could be used by a malicious device to trigger
an OOPS:

Unable to handle kernel NULL pointer dereference at virtual address 00000030
...
[<bf0caa84>] (edge_open [io_ti]) from [<bf0b0118>] (serial_port_activate+0x68/0x98 [usbserial])
[<bf0b0118>] (serial_port_activate [usbserial]) from [<c0470ca4>] (tty_port_open+0x9c/0xe8)
[<c0470ca4>] (tty_port_open) from [<bf0b0da0>] (serial_open+0x48/0x6c [usbserial])
[<bf0b0da0>] (serial_open [usbserial]) from [<c0469178>] (tty_open+0xcc/0x5cc)

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index bf8a4f432f4b..3b1cfba0ec84 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -1508,7 +1508,7 @@ stayinbootmode:
         dev_dbg(dev, "%s - STAYING IN BOOT MODE\n", __func__);
         serial->product_info.TiMode = TI_MODE_BOOT;
 
-        return 0;
+        return 1;
 }
 
 static int ti_do_config(struct edgeport_port *port, int feature, int on)
@@ -2560,14 +2560,18 @@ static int edge_startup(struct usb_serial *serial)
 
         mutex_init(&edge_serial->es_lock);
         edge_serial->serial = serial;
+        INIT_DELAYED_WORK(&edge_serial->heartbeat_work, edge_heartbeat_work);
         usb_set_serial_data(serial, edge_serial);
 
         status = download_fw(edge_serial);
-        if (status) {
+        if (status < 0) {
                 kfree(edge_serial);
                 return status;
         }
 
+        if (status > 0)
+                return 1;       /* bind but do not register any ports */
+
         product_id = le16_to_cpu(
                         edge_serial->serial->dev->descriptor.idProduct);
 
@@ -2579,7 +2583,6 @@ static int edge_startup(struct usb_serial *serial)
                 }
         }
 
-        INIT_DELAYED_WORK(&edge_serial->heartbeat_work, edge_heartbeat_work);
         edge_heartbeat_schedule(edge_serial);
 
         return 0;