[PATCH 2/6] HID: roccat-isku: reject short button reports

[Yousef Alhouseen <alhouseenyousef@gmail.com>]

The Isku raw-event path casts button reports to a five-byte structure
and reads the event payload without validating the received size. A
malformed USB device can therefore trigger out-of-bounds reads from a
short report.

Require the complete button report before updating or forwarding it.

Fixes: d41c2a7011df ("HID: roccat: Add support for Isku keyboard")
Cc: stable@vger.kernel.org
Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
---
 drivers/hid/hid-roccat-isku.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hid/hid-roccat-isku.c b/drivers/hid/hid-roccat-isku.c
index 93a49c93ae8c..c65f414b13cd 100644
--- a/drivers/hid/hid-roccat-isku.c
+++ b/drivers/hid/hid-roccat-isku.c
@@ -411,6 +411,10 @@ static int isku_raw_event(struct hid_device *hdev,
 	if (isku == NULL)
 		return 0;
 
+	if (data[0] == ISKU_REPORT_NUMBER_BUTTON &&
+	    size < sizeof(struct isku_report_button))
+		return 0;
+
 	isku_keep_values_up_to_date(isku, data);
 
 	if (isku->roccat_claimed)
-- 
2.54.0