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

PATCH In review Dmitry Torokhov 2 participants 3 messages Jan 31, 2017 – Feb 1, 2017

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Dmitry Torokhov

author maintainer
#0 lore raw

PATCH 1/1 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_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 <[email protected]>

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=191811

Fixes fbae10db0940 ("Input: uinput - rework ABS validation")
Cc [email protected]
Signed-off-by Dmitry Torokhov <[email protected]>
---
 drivers/input/misc/uinput.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
drivers/input/misc/uinput.c +14 -6
index 92595b98e7ed..022be0e22eba 100644
@@ -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) {
Signature · 4 lines
2.11.0.483.g087da7b7c-goog

-- 
Dmitry
Reviewed-by on v1 1/1
#1 lore raw
Quoted 10 lines · Dmitry Torokhov

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

Shouldn't we prevent completely the mix of the 2 versions? If the user used UI_DEV_SETUP, we should probably prevent the use of UI_SET_ABSBIT afterwards, or at least warn it somehow.

But the patch in itself doesn't hurt, so:

Reviewed-by Benjamin Tissoires <[email protected]>

Cheers,
Benjamin

Quoted 47 lines
Reported-by Rodrigo Rivas Costa <[email protected]>

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=191811

Fixes fbae10db0940 ("Input: uinput - rework ABS validation")
Cc [email protected]
Signed-off-by Dmitry Torokhov <[email protected]>
---
 drivers/input/misc/uinput.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
drivers/input/misc/uinput.c +14 -6
index 92595b98e7ed..022be0e22eba 100644
@@ -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) {
Signature · 4 lines
2.11.0.483.g087da7b7c-goog

-- 
Dmitry
author maintainer
#2 lore raw
Quoted 12 lines · Benjamin Tissoires
Quoted 10 lines · Dmitry Torokhov

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_EVBIT, EV_ABS);
        ioctl(ui, UI_SET_ABSBIT, ABS_X);
        ioctl(ui, UI_SET_ABSBIT, ABS_Y);
        ioctl(ui, UI_DEV_CREATE, 0);
Quoted 3 lines

Shouldn't we prevent completely the mix of the 2 versions? If the user used UI_DEV_SETUP, we should probably prevent the use of UI_SET_ABSBIT afterwards, or at least warn it somehow.

Why? If user does not wish to set up parameters of an axis then just using UI_SET_ABSBIT is fine. In fact, I think it would be weird if we allowed all UI_SET_*BIT except for ABS.

Quoted 3 lines

But the patch in itself doesn't hurt, so:

Reviewed-by Benjamin Tissoires <[email protected]>

Thanks.

Signature · 1 line
Dmitry