[PATCH 2/3] HID: logitech-{dj,hidpp}: check report length

[Peter Wu]

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

For the old WTP, I do not have a HID descriptor so just check for the
minimum length in hidpp_raw_event (this can be changed to an inequality
later).

Signed-off-by: Peter Wu <peter@xxxxxxxxxxxxx>
---
Hi,

If you know that the WTP report (ID 2) has a length of 2, then you can change
"<" to "!=" and remove the paragraph from the commit message.

Kind regards,
Peter
---
 drivers/hid/hid-logitech-dj.c    | 16 +++++++++++++++-
 drivers/hid/hid-logitech-hidpp.c | 12 +++++++++---
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index c917ab6..5bc6d80 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -962,10 +962,24 @@ static int logi_dj_raw_event(struct hid_device *hdev,
 
 	switch (data[0]) {
 	case REPORT_ID_DJ_SHORT:
+		if (size != DJREPORT_SHORT_LENGTH) {
+			dev_err(&hdev->dev, "DJ report of bad size (%d)", size);
+			return false;
+		}
 		return logi_dj_dj_event(hdev, report, data, size);
 	case REPORT_ID_HIDPP_SHORT:
-		/* intentional fallthrough */
+		if (size != HIDPP_REPORT_SHORT_LENGTH) {
+			dev_err(&hdev->dev,
+				"Short HID++ report of bad size (%d)", size);
+			return false;
+		}
+		return logi_dj_hidpp_event(hdev, report, data, size);
 	case REPORT_ID_HIDPP_LONG:
+		if (size != HIDPP_REPORT_LONG_LENGTH) {
+			dev_err(&hdev->dev,
+				"Long HID++ report of bad size (%d)", size);
+			return false;
+		}
 		return logi_dj_hidpp_event(hdev, report, data, size);
 	}
 
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index ae23dec..2315358 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -992,11 +992,17 @@ static int hidpp_raw_event(struct hid_device *hdev, struct hid_report *report,
 			return 1;
 		}
 		return hidpp_raw_hidpp_event(hidpp, data, size);
+	case 0x02:
+		if (size < 2) {
+			hid_err(hdev, "Received HID report of bad size (%d)",
+				size);
+			return 1;
+		}
+		if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP)
+			return wtp_raw_event(hdev, data, size);
+		return 1;
 	}
 
-	if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP)
-		return wtp_raw_event(hdev, data, size);
-
 	return 0;
 }
 
-- 
2.1.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/