USB: race fixes for usb-serial, step 2

- take BKL before looking up a driver to associate with a device to make
  sure the module is not unloaded after looking up but before association
  & bumping module count

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 3780362eb9f0..685fb69bcc32 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -685,14 +685,17 @@ int usb_serial_probe(struct usb_interface *interface,
         int num_ports = 0;
         int max_endpoints;
 
+        lock_kernel(); /* guard against unloading a serial driver module */
         type = search_serial_device(interface);
         if (!type) {
+                unlock_kernel();
                 dbg("none matched");
                 return -ENODEV;
         }
 
         serial = create_serial (dev, interface, type);
         if (!serial) {
+                unlock_kernel();
                 dev_err(&interface->dev, "%s - out of memory\n", __FUNCTION__);
                 return -ENOMEM;
         }
@@ -702,6 +705,7 @@ int usb_serial_probe(struct usb_interface *interface,
                 const struct usb_device_id *id;
 
                 if (!try_module_get(type->driver.owner)) {
+                        unlock_kernel();
                         dev_err(&interface->dev, "module get failed, exiting\n");
                         kfree (serial);
                         return -EIO;
@@ -712,6 +716,7 @@ int usb_serial_probe(struct usb_interface *interface,
                 module_put(type->driver.owner);
 
                 if (retval) {
+                        unlock_kernel();
                         dbg ("sub driver rejected device");
                         kfree (serial);
                         return retval;
@@ -781,6 +786,7 @@ int usb_serial_probe(struct usb_interface *interface,
                  * properly during a later invocation of usb_serial_probe
                  */
                 if (num_bulk_in == 0 || num_bulk_out == 0) {
+                        unlock_kernel();
                         dev_info(&interface->dev, "PL-2303 hack: descriptors matched but endpoints did not\n");
                         kfree (serial);
                         return -ENODEV;
@@ -796,6 +802,7 @@ int usb_serial_probe(struct usb_interface *interface,
         if (type == &usb_serial_generic_device) {
                 num_ports = num_bulk_out;
                 if (num_ports == 0) {
+                        unlock_kernel();
                         dev_err(&interface->dev, "Generic device with no bulk out, not allowed.\n");
                         kfree (serial);
                         return -EIO;
@@ -806,6 +813,7 @@ int usb_serial_probe(struct usb_interface *interface,
                 /* if this device type has a calc_num_ports function, call it */
                 if (type->calc_num_ports) {
                         if (!try_module_get(type->driver.owner)) {
+                                unlock_kernel();
                                 dev_err(&interface->dev, "module get failed, exiting\n");
                                 kfree (serial);
                                 return -EIO;
@@ -831,6 +839,8 @@ int usb_serial_probe(struct usb_interface *interface,
         max_endpoints = max(max_endpoints, num_interrupt_out);
         max_endpoints = max(max_endpoints, (int)serial->num_ports);
         serial->num_port_pointers = max_endpoints;
+        unlock_kernel();
+
         dbg("%s - setting up %d port structures for this device", __FUNCTION__, max_endpoints);
         for (i = 0; i < max_endpoints; ++i) {
                 port = kzalloc(sizeof(struct usb_serial_port), GFP_KERNEL);
@@ -1187,7 +1197,7 @@ static void fixup_generic(struct usb_serial_driver *device)
         set_to_generic_if_null(device, shutdown);
 }
 
-int usb_serial_register(struct usb_serial_driver *driver)
+int usb_serial_register(struct usb_serial_driver *driver) /* must be called with BKL held */
 {
         int retval;
 
@@ -1211,7 +1221,7 @@ int usb_serial_register(struct usb_serial_driver *driver)
 }
 
 
-void usb_serial_deregister(struct usb_serial_driver *device)
+void usb_serial_deregister(struct usb_serial_driver *device) /* must be called with BKL held */
 {
         info("USB Serial deregistering driver %s", device->description);
         list_del(&device->driver_list);