linux-kernel - [PATCH 4.18 150/228] usb: roles: Take care of driver module reference counting

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Message-Id: <20181002132509.254108157@linuxfoundation.org>
Date:   Tue,  2 Oct 2018 06:24:07 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: [PATCH 4.18 150/228] usb: roles: Take care of driver module reference counting

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

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

From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

commit 5c54fcac9a9de559b444ac63ec3cd82f1d157a0b upstream.

This fixes potential "BUG: unable to handle kernel paging
request at ..." from happening.

Cc: <stable@...r.kernel.org>
Acked-by: Hans de Goede <hdegoede@...hat.com>
Tested-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/common/roles.c |   15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

--- a/drivers/usb/common/roles.c
+++ b/drivers/usb/common/roles.c
@@ -109,8 +109,15 @@ static void *usb_role_switch_match(struc
  */
 struct usb_role_switch *usb_role_switch_get(struct device *dev)
 {
-	return device_connection_find_match(dev, "usb-role-switch", NULL,
-					    usb_role_switch_match);
+	struct usb_role_switch *sw;
+
+	sw = device_connection_find_match(dev, "usb-role-switch", NULL,
+					  usb_role_switch_match);
+
+	if (!IS_ERR_OR_NULL(sw))
+		WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
+
+	return sw;
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_get);
 
@@ -122,8 +129,10 @@ EXPORT_SYMBOL_GPL(usb_role_switch_get);
  */
 void usb_role_switch_put(struct usb_role_switch *sw)
 {
-	if (!IS_ERR_OR_NULL(sw))
+	if (!IS_ERR_OR_NULL(sw)) {
 		put_device(&sw->dev);
+		module_put(sw->dev.parent->driver->owner);
+	}
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_put);