HID: magicmouse: Do not crash on missing msc->input

Fake USB devices can send their own report descriptors for which the
input_mapping() hook does not get called.  In this case, msc->input stays NULL,
leading to a crash at a later time.

Detect this condition in the input_configured() hook and reject the device.

This is not supposed to happen with actual magic mouse devices, but can be
provoked by imposing as a magic mouse USB device.

Cc: stable@vger.kernel.org
Signed-off-by: Günther Noack <gnoack@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index 7d4a25c6de0eb7d36ad26a867004d58a1b6eae71..91f621ceb924bac591acfff685fd82c0e72029ed 100644 (file)
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -725,6 +725,11 @@ static int magicmouse_input_configured(struct hid_device *hdev,
        struct magicmouse_sc *msc = hid_get_drvdata(hdev);
        int ret;
 
+       if (!msc->input) {
+               hid_err(hdev, "magicmouse setup input failed (no input)");
+               return -EINVAL;
+       }
+
        ret = magicmouse_setup_input(msc->input, hdev);
        if (ret) {
                hid_err(hdev, "magicmouse setup input failed (%d)\n", ret);