HID: rmi: Check that the RMI_STARTED bit is set before unregistering the RMI transpor...

In the event that the RMI device is unreachable, the calls to rmi_set_mode() or
rmi_set_page() will fail before registering the RMI transport device. When the
device is removed, rmi_remove() will call rmi_unregister_transport_device()
which will attempt to access the rmi_dev pointer which was not set.
This patch adds a check of the RMI_STARTED bit before calling
rmi_unregister_transport_device().  The RMI_STARTED bit is only set
after rmi_register_transport_device() completes successfully.

The kernel oops was reported in this message:
https://www.spinics.net/lists/linux-input/msg58433.html

[jkosina@suse.cz: reworded changelog as agreed with Andrew]
Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Reported-by: Federico Cerutti <federico@ceres-c.it>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index 7c6abd7e09797c8974dfb4f0db3551169a4d478c..9ce22acdfaca261ccf9736794ba9581d0257e119 100644 (file)
--- a/drivers/hid/hid-rmi.c
+++ b/drivers/hid/hid-rmi.c
@@ -744,7 +744,8 @@ static void rmi_remove(struct hid_device *hdev)
 {
        struct rmi_data *hdata = hid_get_drvdata(hdev);
 
-       if (hdata->device_flags & RMI_DEVICE) {
+       if ((hdata->device_flags & RMI_DEVICE)
+           && test_bit(RMI_STARTED, &hdata->flags)) {
                clear_bit(RMI_STARTED, &hdata->flags);
                cancel_work_sync(&hdata->reset_work);
                rmi_unregister_transport_device(&hdata->xport);