Input: gtco - fix endpoint sanity check

commit a8eeb74df5a6bdb214b2b581b14782c5f5a0cf83 upstream.

The driver was checking the number of endpoints of the first alternate
setting instead of the current one, something which could lead to the
driver binding to an invalid interface.

This in turn could cause the driver to misbehave or trigger a WARN() in
usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 162f98dea487 ("Input: gtco - fix crash on detecting device without endpoints")
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Vladis Dronov <vdronov@redhat.com>
Link: https://lore.kernel.org/r/20191210113737.4016-5-johan@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index cf3af3a3297a684ed15759b5d627a2d0ebdec525..a0f69a015e0e031bcc5a927fdad90a608840b395 100644 (file)
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -886,18 +886,14 @@ static int gtco_probe(struct usb_interface *usbinterface,
        }
 
        /* Sanity check that a device has an endpoint */
-       if (usbinterface->altsetting[0].desc.bNumEndpoints < 1) {
+       if (usbinterface->cur_altsetting->desc.bNumEndpoints < 1) {
                dev_err(&usbinterface->dev,
                        "Invalid number of endpoints\n");
                error = -EINVAL;
                goto err_free_urb;
        }
 
-       /*
-        * The endpoint is always altsetting 0, we know this since we know
-        * this device only has one interrupt endpoint
-        */
-       endpoint = &usbinterface->altsetting[0].endpoint[0].desc;
+       endpoint = &usbinterface->cur_altsetting->endpoint[0].desc;
 
        /* Some debug */
        dev_dbg(&usbinterface->dev, "gtco # interfaces: %d\n", usbinterface->num_altsetting);
@@ -984,7 +980,7 @@ static int gtco_probe(struct usb_interface *usbinterface,
        input_dev->dev.parent = &usbinterface->dev;
 
        /* Setup the URB, it will be posted later on open of input device */
-       endpoint = &usbinterface->altsetting[0].endpoint[0].desc;
+       endpoint = &usbinterface->cur_altsetting->endpoint[0].desc;
 
        usb_fill_int_urb(gtco->urbinfo,
                         gtco->usbdev,