Fix an abort if the device speed is NaN

When using libinput with xf86-input-libinput, the device speed is
represented as a float passed via X properties.

If a buggy client gives a broken value, the conversions that occur
can cause the value of speed to be NaN (not a number), aka infinity.

In C, any comparison with NaN always gives false, whatever the value.

So that test in libinput_device_config_accel_set_speed():

   (speed < 1.0 || speed > 1.0)

will necessarily return FALSE, defeating the test of range.

However, since since any comparison with NaN is false, the
opposite assert() in accelerator_set_speed():

   (speed >= 1.0 && speed <= 1.0)

will be false as well, thus triggering the abort() and the crash of
the entire X server along with it.

The solution is to use the same construct in both routines, so that
it fails gracefully in libinput_device_config_accel_set_speed().

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/test/pointer.c b/test/pointer.c
index 9a1e9d6c..2e52a206 100644
--- a/test/pointer.c
+++ b/test/pointer.c
@@ -770,6 +770,23 @@ START_TEST(pointer_accel_defaults)
 }
 END_TEST
 
+START_TEST(pointer_accel_invalid)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput_device *device = dev->libinput_device;
+	enum libinput_config_status status;
+
+	ck_assert(libinput_device_config_accel_is_available(device));
+
+	status = libinput_device_config_accel_set_speed(device,
+							NAN);
+	ck_assert_int_eq(status, LIBINPUT_CONFIG_STATUS_INVALID);
+	status = libinput_device_config_accel_set_speed(device,
+							INFINITY);
+	ck_assert_int_eq(status, LIBINPUT_CONFIG_STATUS_INVALID);
+}
+END_TEST
+
 START_TEST(pointer_accel_defaults_absolute)
 {
 	struct litest_device *dev = litest_current_device();
@@ -818,6 +835,7 @@ int main (int argc, char **argv) {
 	litest_add("pointer:left-handed", pointer_left_handed_during_click_multiple_buttons, LITEST_RELATIVE|LITEST_BUTTON, LITEST_ANY);
 
 	litest_add("pointer:accel", pointer_accel_defaults, LITEST_RELATIVE, LITEST_ANY);
+	litest_add("pointer:accel", pointer_accel_invalid, LITEST_RELATIVE, LITEST_ANY);
 	litest_add("pointer:accel", pointer_accel_defaults_absolute, LITEST_ABSOLUTE, LITEST_ANY);
 
 	return litest_run(argc, argv);