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

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@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=191811
Fixes: fbae10db0940 ("Input: uinput - rework ABS validation")
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 92595b98e7ed..022be0e22eba 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -263,13 +263,21 @@ static int uinput_create_device(struct uinput_device *udev)
                 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) {