[PATCH 5.4 047/177] usb: roles: fix a potential use after free

[Greg Kroah-Hartman]

From: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>

commit 1848a543191ae32e558bb0a5974ae7c38ebd86fc upstream.

Free the sw structure only after we are done using it.
This patch just moves the put_device() down a bit to avoid the
use after free.

Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting")
Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Reviewed-by: Peter Chen <peter.chen@xxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Cc: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20191124142236.25671-1-wenyang@xxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/roles/class.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -169,8 +169,8 @@ EXPORT_SYMBOL_GPL(fwnode_usb_role_switch
 void usb_role_switch_put(struct usb_role_switch *sw)
 {
 	if (!IS_ERR_OR_NULL(sw)) {
-		put_device(&sw->dev);
 		module_put(sw->dev.parent->driver->owner);
+		put_device(&sw->dev);
 	}
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_put);