[PATCH v4 6/6] HID: wacom: add NULL touch_input guards to remaining touch handlers

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

wacom_24hdt_irq() (also handles WACOM_27QHDT), wacom_intuos_pro2_bt_touch(),
and wacom_bamboo_pad_touch_event() dereference wacom->touch_input without
checking it.

As with the other handlers in this series, touch_input can be NULL when
wacom_setup_touch_input_capabilities() returns -ENODEV during an
otherwise successful probe.

Fixes: 2a6cdbdd4cc0 ("HID: wacom: Introduce new 'touch_input' device")
Cc: stable@vger.kernel.org
Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 drivers/hid/wacom_wac.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index c4d6295f57c9..38003e0b8083 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1489,6 +1489,12 @@ static void wacom_intuos_pro2_bt_touch(struct wacom_wac *wacom)
 	int num_contacts_left = 5;
 	int i, j;
 
+	if (!touch_input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: touch_input is NULL\n", __func__);
+		return;
+	}
+
 	for (i = 0; i < finger_frames; i++) {
 		unsigned char *frame = &data[i*finger_frame_len + 109];
 		int current_num_contacts = frame[0] & 0x7F;
@@ -1660,6 +1666,12 @@ static int wacom_24hdt_irq(struct wacom_wac *wacom)
 	int byte_per_packet = WACOM_BYTES_PER_24HDT_PACKET;
 	int y_offset = 2;
 
+	if (!input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: touch_input is NULL\n", __func__);
+		return 0;
+	}
+
 	if (touch_is_muted(wacom) && !wacom->shared->touch_down)
 		return 0;
 
@@ -3430,6 +3442,12 @@ static int wacom_bamboo_pad_touch_event(struct wacom_wac *wacom,
 	int x, y;
 	bool valid;
 
+	if (!input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: touch_input is NULL\n", __func__);
+		return 0;
+	}
+
 	prefix = data[0];
 
 	for (id = 0; id < wacom->features.touch_max; id++) {
-- 
2.53.0