HID: wacom: Use ktime_t rather than int when dealing with timestamps

Code which interacts with timestamps needs to use the ktime_t type
returned by functions like ktime_get. The int type does not offer
enough space to store these values, and attempting to use it is a
recipe for problems. In this particular case, overflows would occur
when calculating/storing timestamps leading to incorrect values being
reported to userspace. In some cases these bad timestamps cause input
handling in userspace to appear hung.

Link: https://gitlab.freedesktop.org/libinput/libinput/-/issues/901
Fixes: 17d793f3ed53 ("HID: wacom: insert timestamp to packed Bluetooth (BT) events")
CC: stable@vger.kernel.org
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20230608213828.2108-1-jason.gerecke@wacom.com
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
[jason.gerecke@wacom.com: Imported into input-wacom repository (9a6c0e28e215)]
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>

4.5/wacom_wac.c

@@ -1325,7 +1325,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 	unsigned char *data = wacom->data;
 	int number_of_valid_frames = 0;
 #ifdef WACOM_INPUT_SET_TIMESTAMP
-	int time_interval = 15000000;
+	ktime_t time_interval = 15000000;
 	ktime_t time_packet_received = ktime_get();
 #endif
 	int i;
@@ -1361,7 +1361,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 	if (number_of_valid_frames) {
 		if (wacom->hid_data.time_delayed)
 			time_interval = ktime_get() - wacom->hid_data.time_delayed;
-		time_interval /= number_of_valid_frames;
+		time_interval = div_u64(time_interval, number_of_valid_frames);
 		wacom->hid_data.time_delayed = time_packet_received;
 	}
 #endif
@@ -1374,7 +1374,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 		bool invert = frame[0] & 0x10;
 #ifdef WACOM_INPUT_SET_TIMESTAMP
 		int frames_number_reversed = number_of_valid_frames - i - 1;
-		int event_timestamp = time_packet_received - frames_number_reversed * time_interval;
+		ktime_t event_timestamp = time_packet_received - frames_number_reversed * time_interval;
 #endif
 
 		if (!valid)
@@ -1388,7 +1388,9 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 			wacom->tool[0] = 0;
 			wacom->id[0] = 0;
 			wacom->serial[0] = 0;
+#ifdef WACOM_INPUT_SET_TIMESTAMP
 			wacom->hid_data.time_delayed = 0;
+#endif
 			return;
 		}
 

4.5/wacom_wac.h

@@ -3,6 +3,8 @@
 #ifndef WACOM_WAC_H
 #define WACOM_WAC_H
 
+#include "../config.h"
+
 #include <linux/types.h>
 #include <linux/hid.h>
 #include <linux/kfifo.h>
@@ -348,7 +350,9 @@ struct hid_data {
 	int ps_connected;
 	bool pad_input_event_flag;
 	unsigned short sequence_number;
-	int time_delayed;
+#ifdef WACOM_INPUT_SET_TIMESTAMP
+	ktime_t time_delayed;
+#endif
 };
 
 struct wacom_remote_data {