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[v3,3/7] HID: lenovo: Check hid_get_drvdata() returns non NULL in lenovo_event()

Message ID 20210221112005.102116-4-hdegoede@redhat.com (mailing list archive)
State New, archived
Headers show
Series HID: lenovo: Mute LED handling fixes and improvements | expand

Commit Message

Hans de Goede Feb. 21, 2021, 11:20 a.m. UTC
The HID lenovo probe function only attaches drvdata to one of the
USB interfaces, but lenovo_event() will get called for all USB interfaces
to which hid-lenovo is bound.

This allows a malicious device to fake being a device handled by
hid-lenovo, which generates events for which lenovo_event() has
special handling (and thus dereferences hid_get_drvdata()) on another
interface triggering a NULL pointer exception.

Add a check for hid_get_drvdata() returning NULL, avoiding this
possible NULL pointer exception.

Fixes: bc04b37ea0ec ("HID: lenovo: Add ThinkPad 10 Ultrabook Keyboard support")
Reviewed-by: Marek BehĂșn <kabel@kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
 drivers/hid/hid-lenovo.c | 3 +++
 1 file changed, 3 insertions(+)
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diff --git a/drivers/hid/hid-lenovo.c b/drivers/hid/hid-lenovo.c
index ee175ab54281..b2596ed37880 100644
--- a/drivers/hid/hid-lenovo.c
+++ b/drivers/hid/hid-lenovo.c
@@ -508,6 +508,9 @@  static int lenovo_event_cptkbd(struct hid_device *hdev,
 static int lenovo_event(struct hid_device *hdev, struct hid_field *field,
 		struct hid_usage *usage, __s32 value)
+	if (!hid_get_drvdata(hdev))
+		return 0;
 	switch (hdev->product) {