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>

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 2ccf838371343da1628bec555896caba7843d2eb..174bf03908d7c4d108bfeb0c6c494bd3d4cfe93f 100644 (file)
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1314,7 +1314,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
        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;
 
@@ -1348,7 +1348,7 @@ 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;
        }
 
@@ -1359,7 +1359,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
                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;

diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index 1a40bb8c5810ce560e2da9e4bfac1fa3c186938f..ee21bb260f22f83b85ff1ea66659595aa69d92bd 100644 (file)
--- 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 {