Input: uinput - fix crash when mixing old and new init style

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@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=191811
Fixes: fbae10db ("Input: uinput - rework ABS validation")
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/uinput.c

@@ -263,6 +263,13 @@ static int uinput_create_device(struct uinput_device *udev)
 		return -EINVAL;
 	}
 
+	if (test_bit(EV_ABS, dev->evbit)) {
+		input_alloc_absinfo(dev);
+		if (!dev->absinfo) {
+			error = -EINVAL;
+			goto fail1;
+		}
+
 		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);
@@ -271,6 +278,7 @@ static int uinput_create_device(struct uinput_device *udev)
 		} 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) {
 		printk(KERN_DEBUG "%s: ff_effects_max should be non-zero when FF_BIT is set\n",