[PATCH xf86-input-libinput v3] Ignore property changes if the device is disabled

[Olivier Fourdan]

If the device is present but disabled, the server will still call into
SetProperty. We don't have a libinput device to back it up in this case,
causing a null-pointer dereference.

This is a bug specific to this driver that cannot easily be fixed. All
other drivers can handle property changes even if no device is present,
here we rely on libinput to make the final call. But without a device
path/fd we don't have a libinput reference.

The protocol doesn't mention this case, so let's pick BadMatch as the
least wrong error code. And put a warning in the log, this needs a
workaround in the client.

Also, if we get here and the device is on, then that's definitely a bug,
warn about that.

https://bugs.freedesktop.org/show_bug.cgi?id=89296

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

 v3: Check for valid device only for libinput properties

 src/libinput.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/src/libinput.c b/src/libinput.c
index 9613fbd..9afa6d1 100644
--- a/src/libinput.c
+++ b/src/libinput.c
@@ -1293,6 +1293,26 @@ static Atom prop_float;
 static Atom prop_device;
 static Atom prop_product_id;
 
+static inline BOOL
+xf86libinput_check_device (DeviceIntPtr dev,
+			   Atom atom)
+{
+	InputInfoPtr pInfo = dev->public.devicePrivate;
+	struct xf86libinput *driver_data = pInfo->private;
+	struct libinput_device *device = driver_data->device;
+
+	if (device == NULL) {
+		BUG_WARN(dev->public.on);
+		xf86IDrvMsg(pInfo, X_INFO,
+			    "SetProperty on %d called but device is disabled.\n"
+			    "This driver cannot change properties on a disabled device\n",
+			    atom);
+		return FALSE;
+	}
+
+	return TRUE;
+}
+
 static inline int
 LibinputSetPropertyTap(DeviceIntPtr dev,
                        Atom atom,
@@ -1312,6 +1332,9 @@ LibinputSetPropertyTap(DeviceIntPtr dev,
 		if (*data != 0 && *data != 1)
 			return BadValue;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
 		if (libinput_device_config_tap_get_finger_count(device) == 0)
 			return BadMatch;
 	} else {
@@ -1343,6 +1366,9 @@ LibinputSetPropertyCalibration(DeviceIntPtr dev,
 		    data[8] != 1)
 			return BadValue;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
 		if (!libinput_device_config_calibration_has_matrix(device))
 			return BadMatch;
 	} else {
@@ -1374,6 +1400,9 @@ LibinputSetPropertyAccel(DeviceIntPtr dev,
 		if (*data < -1 || *data > 1)
 			return BadValue;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
 		if (libinput_device_config_accel_is_available(device) == 0)
 			return BadMatch;
 	} else {
@@ -1403,6 +1432,9 @@ LibinputSetPropertyNaturalScroll(DeviceIntPtr dev,
 		if (*data != 0 && *data != 1)
 			return BadValue;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
 		if (libinput_device_config_scroll_has_natural_scroll(device) == 0)
 			return BadMatch;
 	} else {
@@ -1435,9 +1467,12 @@ LibinputSetPropertySendEvents(DeviceIntPtr dev,
 		modes |= LIBINPUT_CONFIG_SEND_EVENTS_DISABLED_ON_EXTERNAL_MOUSE;
 
 	if (checkonly) {
-		uint32_t supported =
-			libinput_device_config_send_events_get_modes(device);
+		uint32_t supported;
+
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
 
+		supported = libinput_device_config_send_events_get_modes(device);
 		if ((modes | supported) != supported)
 			return BadValue;
 
@@ -1465,9 +1500,13 @@ LibinputSetPropertyLeftHanded(DeviceIntPtr dev,
 	data = (BOOL*)val->data;
 
 	if (checkonly) {
-		int supported = libinput_device_config_left_handed_is_available(device);
+		int supported;
 		int left_handed = *data;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
+		supported = libinput_device_config_left_handed_is_available(device);
 		if (!supported && left_handed)
 			return BadValue;
 	} else {
@@ -1502,11 +1541,15 @@ LibinputSetPropertyScrollMethods(DeviceIntPtr dev,
 		modes |= LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN;
 
 	if (checkonly) {
-		uint32_t supported = libinput_device_config_scroll_get_methods(device);
+		uint32_t supported;
 
 		if (__builtin_popcount(modes) > 1)
 			return BadValue;
 
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
+
+		supported = libinput_device_config_scroll_get_methods(device);
 		if (modes && (modes & supported) == 0)
 			return BadValue;
 	} else {
@@ -1534,9 +1577,13 @@ LibinputSetPropertyScrollButton(DeviceIntPtr dev,
 
 	if (checkonly) {
 		uint32_t button = *data;
-		uint32_t supported = libinput_device_has_button(device,
-								btn_xorg2linux(button));
+		uint32_t supported;
+
+		if (!xf86libinput_check_device (dev, atom))
+			return BadMatch;
 
+		supported = libinput_device_has_button(device,
+						       btn_xorg2linux(button));
 		if (button && !supported)
 			return BadValue;
 	} else {
-- 
2.1.0