[PATCH v2 5/5] HID: wacom: add NULL input guards to Bamboo touch/button handlers

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

wacom_bpt_touch() dereferences both touch_input and pad_input.
wacom_bpt3_touch_msg() dereferences touch_input.
wacom_bpt3_button_msg() dereferences pad_input.

All three can be NULL when the corresponding
wacom_setup_{touch,pad}_input_capabilities() returns -ENODEV during a
successful probe. Add per-function guards.

Fixes: 2a6cdbdd4cc0 ("HID: wacom: Introduce new 'touch_input' device")
Fixes: 862cf5535c0c ("HID: wacom: Introduce a new WACOM_DEVICETYPE_PAD device_type")
Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 drivers/hid/wacom_wac.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 12a632ee1cbf..21c2504a085a 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -3148,6 +3148,12 @@ static int wacom_bpt_touch(struct wacom_wac *wacom)
 	if (data[0] != 0x02)
 	    return 0;
 
+	if (!input || !pad_input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: input is NULL\n", __func__);
+		return 0;
+	}
+
 	for (i = 0; i < 2; i++) {
 		int offset = (data[1] & 0x80) ? (8 * i) : (9 * i);
 		bool touch = report_touch_events(wacom)
@@ -3182,8 +3188,17 @@ static void wacom_bpt3_touch_msg(struct wacom_wac *wacom, unsigned char *data)
 {
 	struct wacom_features *features = &wacom->features;
 	struct input_dev *input = wacom->touch_input;
-	bool touch = data[1] & 0x80;
-	int slot = input_mt_get_slot_by_key(input, data[0]);
+	bool touch;
+	int slot;
+
+	if (!input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: touch_input is NULL\n", __func__);
+		return;
+	}
+
+	touch = data[1] & 0x80;
+	slot = input_mt_get_slot_by_key(input, data[0]);
 
 	if (slot < 0)
 		return;
@@ -3226,6 +3241,12 @@ static void wacom_bpt3_button_msg(struct wacom_wac *wacom, unsigned char *data)
 	struct input_dev *input = wacom->pad_input;
 	struct wacom_features *features = &wacom->features;
 
+	if (!input) {
+		dev_warn_once(&container_of(wacom, struct wacom, wacom_wac)->hdev->dev,
+			      "%s: pad_input is NULL\n", __func__);
+		return;
+	}
+
 	if (features->type == INTUOSHT || features->type == INTUOSHT2) {
 		input_report_key(input, BTN_LEFT, (data[1] & 0x02) != 0);
 		input_report_key(input, BTN_BACK, (data[1] & 0x08) != 0);
-- 
2.53.0