From eea702e30a890dd3ac3d962474117365bf205876 Mon Sep 17 00:00:00 2001 From: Peter Hutterer Date: Mon, 22 Mar 2021 13:55:34 +1000 Subject: [PATCH] evdev: don't check the event time if it's higher than the dispatch time The dispatch time is taken during libinput_dispatch(), i.e. at the beginning of an event sequence. We always read all events off the device, so where events come in while we're inside the main dispatch loop, our event time may be later than the saved dispatch_time. This causes an uint underflow and our tdelta > 10 will be true for that case. Signed-off-by: Peter Hutterer (cherry picked from commit 95a72990ad71285b834646210c5a483baabd4b4e) --- src/evdev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/src/evdev.c b/src/evdev.c index d792e8aa..14796e83 100644 --- a/src/evdev.c +++ b/src/evdev.c @@ -1024,6 +1024,7 @@ evdev_note_time_delay(struct evdev_device *device, { struct libinput *libinput = evdev_libinput_context(device); uint32_t tdelta; + uint32_t eventtime = input_event_time(ev); /* if we have a current libinput_dispatch() snapshot, compare our * event time with the one from the snapshot. If we have more than @@ -1031,10 +1032,11 @@ evdev_note_time_delay(struct evdev_device *device, * where there is no steady event flow and thus SYN_DROPPED may not * get hit by the kernel despite us being too slow. */ - if (libinput->dispatch_time == 0) + if (libinput->dispatch_time == 0 || + eventtime > libinput->dispatch_time) return; - tdelta = us2ms(libinput->dispatch_time - input_event_time(ev)); + tdelta = us2ms(libinput->dispatch_time - eventtime); if (tdelta > 10) { evdev_log_bug_client_ratelimit(device, &device->delay_warning_limit,