On Wed, Jun 21, 2023 at 9:04 AM Benjamin Tissoires benjamin.tissoires@redhat.com wrote:

On Wed, Jun 21, 2023 at 5:18 PM Jason Gerecke killertofu@gmail.com wrote:

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Following up since no action seems to have been taken on this patch yet.

Sorry, this went through the cracks (I seem to have a lot of cracks recently...)

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On Thu, Jun 8, 2023 at 2:38 PM Jason Gerecke killertofu@gmail.com wrote:

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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.

I have to ask, is this something we should consider writing a test for? :)

Very good point! I'm happy to work on such a test.

Are you open to merging this patch without delay while I write a testcase? I don't like the idea of this (apparent) system freeze being affecting users any longer than absolutely necessary.

Also, you are missing the rev-by from Peter, not sure if the tools will pick it up automatically then.

Reviewed-by: Benjamin Tissoires benjamin.tissoires@redhat.com

Oof, good catch. Apologies to Peter :)

Jason

Cheers, Benjamin

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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

---

v2: Use div_u64 to perform division to deal with ARC and ARM architectures (as found by the kernel test robot)

drivers/hid/wacom_wac.c | 6 +++--- drivers/hid/wacom_wac.h | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index 2ccf838371343..174bf03908d7c 100644 --- 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 1a40bb8c5810c..ee21bb260f22f 100644 --- 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 {

2.41.0