HID: hid-uclogic-params: Invalid parameter check in uclogic_params_init

[ Upstream commit f364c571a5c77e96de2d32062ff019d6b8d2e2bc ]

The function performs a check on its input parameters, however, the
hdev parameter is used before the check.

Initialize the stack variables after checking the input parameters to
avoid a possible NULL pointer dereference.

Fixes: 9614219e9310e ("HID: uclogic: Extract tablet parameter discovery into a module")
Addresses-Coverity-ID: 1443831 ("Null pointer dereference")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/hid/hid-uclogic-params.c b/drivers/hid/hid-uclogic-params.c
index adff1bd..3c10b85 100644 (file)
--- a/drivers/hid/hid-uclogic-params.c
+++ b/drivers/hid/hid-uclogic-params.c
@@ -834,10 +834,10 @@ int uclogic_params_init(struct uclogic_params *params,
                        struct hid_device *hdev)
 {
        int rc;
-       struct usb_device *udev = hid_to_usb_dev(hdev);
-       __u8  bNumInterfaces = udev->config->desc.bNumInterfaces;
-       struct usb_interface *iface = to_usb_interface(hdev->dev.parent);
-       __u8 bInterfaceNumber = iface->cur_altsetting->desc.bInterfaceNumber;
+       struct usb_device *udev;
+       __u8  bNumInterfaces;
+       struct usb_interface *iface;
+       __u8 bInterfaceNumber;
        bool found;
        /* The resulting parameters (noop) */
        struct uclogic_params p = {0, };
@@ -848,6 +848,11 @@ int uclogic_params_init(struct uclogic_params *params,
                goto cleanup;
        }
 
+       udev = hid_to_usb_dev(hdev);
+       bNumInterfaces = udev->config->desc.bNumInterfaces;
+       iface = to_usb_interface(hdev->dev.parent);
+       bInterfaceNumber = iface->cur_altsetting->desc.bInterfaceNumber;
+
        /*
         * Set replacement report descriptor if the original matches the
         * specified size. Otherwise keep interface unchanged.