[PATCH 4.9 13/60] Input: uinput - fix crash when mixing old and new init style

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

commit 601bbbe0517303c9f8eb3d75e11d64efed1293c9 upstream.

If user tries to initialize uinput device mixing old and new style
initialization (i.e. using old UI_SET_ABSBIT instead of UI_ABS_SETUP,
we forget to allocate input->absinfo and will crash when trying to send
absolute events:

        ioctl(ui, UI_DEV_SETUP, &us);
        ioctl(ui, UI_SET_PHYS, "Test");

        ioctl(ui, UI_SET_EVBIT, EV_ABS);
        ioctl(ui, UI_SET_ABSBIT, ABS_X);
        ioctl(ui, UI_SET_ABSBIT, ABS_Y);
        ioctl(ui, UI_DEV_CREATE, 0);

Reported-by: Rodrigo Rivas Costa <rodrigorivascosta@xxxxxxxxx>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=191811
Fixes: fbae10db0940 ("Input: uinput - rework ABS validation")
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/input/misc/uinput.c |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -263,13 +263,21 @@ static int uinput_create_device(struct u
 		return -EINVAL;
 	}
 
-	if (test_bit(ABS_MT_SLOT, dev->absbit)) {
-		nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
-		error = input_mt_init_slots(dev, nslot, 0);
-		if (error)
+	if (test_bit(EV_ABS, dev->evbit)) {
+		input_alloc_absinfo(dev);
+		if (!dev->absinfo) {
+			error = -EINVAL;
 			goto fail1;
-	} else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
-		input_set_events_per_packet(dev, 60);
+		}
+
+		if (test_bit(ABS_MT_SLOT, dev->absbit)) {
+			nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
+			error = input_mt_init_slots(dev, nslot, 0);
+			if (error)
+				goto fail1;
+		} else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
+			input_set_events_per_packet(dev, 60);
+		}
 	}
 
 	if (test_bit(EV_FF, dev->evbit) && !udev->ff_effects_max) {