[PATCH v2 2/3] HID: logitech-hidpp: check WTP report length

[Peter Wu <peter@lekensteyn.nl>]

Malicious USB devices can send bogus reports smaller than the expected
buffer size. Ensure that the length for WTP reports is valid to avoid
reading out of bounds.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
---
 v1: patch 2/3 HID: logitech-{dj,hidpp}: check report length
 v2: splitted original report length check patch
---
 drivers/hid/hid-logitech-hidpp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index b32f751..2f1b0ac 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -805,6 +805,11 @@ static int wtp_raw_event(struct hid_device *hdev, u8 *data, int size)
 
 	switch (data[0]) {
 	case 0x02:
+		if (size < 2) {
+			hid_err(hdev, "Received HID report of bad size (%d)",
+				size);
+			return 1;
+		}
 		if (hidpp->quirks & HIDPP_QUIRK_WTP_PHYSICAL_BUTTONS) {
 			input_event(wd->input, EV_KEY, BTN_LEFT,
 					!!(data[1] & 0x01));
@@ -818,6 +823,7 @@ static int wtp_raw_event(struct hid_device *hdev, u8 *data, int size)
 			return wtp_mouse_raw_xy_event(hidpp, &data[7]);
 		}
 	case REPORT_ID_HIDPP_LONG:
+		/* size is already checked in hidpp_raw_event. */
 		if ((report->fap.feature_index != wd->mt_feature_index) ||
 		    (report->fap.funcindex_clientid != EVENT_TOUCHPAD_RAW_XY))
 			return 1;
-- 
2.1.3