[PATCH 6.1 28/30] HID: wacom: Use ktime_t rather than int when dealing with timestamps

Greg Kroah-Hartman
2023-06-29T18:45:35Z

From: Jason Gerecke <jason.gerecke@wacom.com>

commit 9a6c0e28e215535b2938c61ded54603b4e5814c5 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hid/wacom_wac.c | 6 +++---
drivers/hid/wacom_wac.h | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1309,7 +1309,7 @@ static void wacom_intuos_pro2_bt_pen(str
struct input_dev *pen_input = wacom->pen_input;
unsigned char *data = wacom->data;
int number_of_valid_frames = 0;
- int time_interval = 15000000;
+ ktime_t time_interval = 15000000;
ktime_t time_packet_received = ktime_get();
int i;

@@ -1343,7 +1343,7 @@ static void wacom_intuos_pro2_bt_pen(str
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;
}

@@ -1354,7 +1354,7 @@ static void wacom_intuos_pro2_bt_pen(str
bool range = frame[0] & 0x20;
bool invert = frame[0] & 0x10;
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;

if (!valid)
continue;
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -324,7 +324,7 @@ struct hid_data {
int ps_connected;
bool pad_input_event_flag;
unsigned short sequence_number;
- int time_delayed;
+ ktime_t time_delayed;
};

struct wacom_remote_data {