[PATCH v3 3/6] HID: wacom: add NULL pad_input guard to wacom_intuos_pad()

[Jinmo Yang <jinmo44.yang@gmail.com>]

wacom_intuos_pad() uses wacom->pad_input throughout, but pad_input can
be NULL when wacom_setup_pad_input_capabilities() returns -ENODEV during
a successful probe.

Place the guard after the data[0] report-ID check and return 1 so the
report is consumed. Returning 0 would let the caller fall through to
wacom_intuos_inout(), which would misparse the pad packet as a pen
event.

Fixes: 10059cdc0ad0 ("Input: wacom - split out the pad device for Intuos/Cintiq")
Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 drivers/hid/wacom_wac.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index bec8dbec5bc3..65829de86363 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -581,6 +581,12 @@ static int wacom_intuos_pad(struct wacom_wac *wacom)
 	      data[0] == WACOM_REPORT_CINTIQPAD))
 		return 0;
 
+	if (!input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: pad_input is NULL\n", __func__);
+		return 1; /* consume the report to prevent fall-through */
+	}
+
 	if (features->type >= INTUOS4S && features->type <= INTUOS4L) {
 		buttons = (data[3] << 1) | (data[2] & 0x01);
 		ring1 = data[1];
-- 
2.53.0