[PATCH 4/6] HID: roccat-kovaplus: reject short button reports

[Yousef Alhouseen <alhouseenyousef@gmail.com>]

The Kovaplus raw-event helpers cast button reports to a five-byte
structure and read all payload fields without checking the received size.
A malformed USB device can therefore trigger out-of-bounds reads from a
short input report.

Require a complete button report before updating or forwarding it.

Fixes: 0e70f97f257e ("HID: roccat: Add support for Kova[+] mouse")
Cc: stable@vger.kernel.org
Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
---
 drivers/hid/hid-roccat-kovaplus.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hid/hid-roccat-kovaplus.c b/drivers/hid/hid-roccat-kovaplus.c
index 9ec42c218ef9..55de262e165b 100644
--- a/drivers/hid/hid-roccat-kovaplus.c
+++ b/drivers/hid/hid-roccat-kovaplus.c
@@ -614,6 +614,10 @@ static int kovaplus_raw_event(struct hid_device *hdev,
 	if (kovaplus == NULL)
 		return 0;
 
+	if (data[0] == KOVAPLUS_MOUSE_REPORT_NUMBER_BUTTON &&
+	    size < sizeof(struct kovaplus_mouse_report_button))
+		return 0;
+
 	kovaplus_keep_values_up_to_date(kovaplus, data);
 
 	if (kovaplus->roccat_claimed)
-- 
2.54.0