[PATCH 4/4] HID: cp2112: fix out-of-bounds read in cp2112_raw_event

[Jiale Yao]

The TRANSFER_STATUS_RESPONSE path dereferences xfer->length at
offset 6, requiring sizeof(*xfer) bytes.  The DATA_READ_RESPONSE
path uses the device-supplied read_length to drive memcpy()
without clamping it to the remaining report size.  Add both
checks, and clamp read_length to size - 3.

Assisted-by: Claude:deepseek-v4-pro
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 drivers/hid/hid-cp2112.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index 04379db93571..99e31724a421 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -1430,6 +1430,11 @@ static int cp2112_raw_event(struct hid_device *hdev, struct hid_report *report,
 
 	switch (data[0]) {
 	case CP2112_TRANSFER_STATUS_RESPONSE:
+		if (size < sizeof(*xfer)) {
+			hid_err(hdev, "short transfer status report(%d < %zu)\n", size,
+				sizeof(*xfer));
+			return 0;
+		}
 		hid_dbg(hdev, "xfer status: %02x %02x %04x %04x\n",
 			xfer->status0, xfer->status1,
 			be16_to_cpu(xfer->retries), be16_to_cpu(xfer->length));
@@ -1463,12 +1468,18 @@ static int cp2112_raw_event(struct hid_device *hdev, struct hid_report *report,
 		atomic_set(&dev->xfer_avail, 1);
 		break;
 	case CP2112_DATA_READ_RESPONSE:
+		if (size < 4) {
+			hid_err(hdev, "short data read response(%d < 4)\n", size);
+			return 0;
+		}
 		hid_dbg(hdev, "read response: %02x %02x\n", data[1], data[2]);
 
 		dev->read_length = data[2];
 		if (dev->read_length > sizeof(dev->read_data))
 			dev->read_length = sizeof(dev->read_data);
 
+		if (dev->read_length > size - 3)
+			dev->read_length = size - 3;
 		memcpy(dev->read_data, &data[3], dev->read_length);
 		atomic_set(&dev->read_avail, 1);
 		break;
-- 
2.34.1