[PATCH 02/10] HID: cougar: reject short special-key reports

[Jiale Yao]

The HID core invokes raw_event callbacks before validating the report
length.  cougar_raw_event() reads the key code and action from offsets one
and two without checking that those bytes are present.  A short report on
the special interface can therefore cause an out-of-bounds read.

Consume reports that do not contain the action field before accessing the
fixed offsets, consistent with the callback's handling of other reports on
the special interface.

Commit 47669bec44fe ("HID: asus: refactor the two workqueues and init
sequence") added the same kind of raw_event length validation to hid-asus.

Fixes: b8e759b8f6da ("HID: cougar: Add support for the Cougar 500k Gaming Keyboard")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 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++) {
-- 
2.34.1