[PATCH 2/4] HID: cougar: reject short vendor reports

[Yousef Alhouseen <alhouseenyousef@gmail.com>]

cougar_raw_event() reads the key code and action from bytes one and two
of every enabled vendor-interface report. A malformed USB device can
send a shorter report and make both accesses run beyond the received
buffer.

Consume short vendor reports without parsing them.

Fixes: b8e759b8f6da ("HID: cougar: Add support for the Cougar 500k Gaming Keyboard")
Cc: stable@vger.kernel.org
Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
---
 drivers/hid/hid-cougar.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hid/hid-cougar.c b/drivers/hid/hid-cougar.c
index ad027c45f162..7156658166f5 100644
--- a/drivers/hid/hid-cougar.c
+++ b/drivers/hid/hid-cougar.c
@@ -270,6 +270,9 @@ static int cougar_raw_event(struct hid_device *hdev, struct hid_report *report,
 	if (!shared->enabled || !shared->input)
 		return -EPERM;
 
+	if (size <= COUGAR_FIELD_ACTION)
+		return -EPERM;
+
 	code = data[COUGAR_FIELD_CODE];
 	action = data[COUGAR_FIELD_ACTION];
 	for (i = 0; cougar_mapping[i][0]; i++) {
-- 
2.54.0