[PATCH 2/2] HID: intel-thc-hid: intel-quickspi: bound the GET REPORT response to report_buf

quickspi_handle_input_data() copies a GET_FEATURE or GET_INPUT_REPORT
response into qsdev->report_buf using a length the controller supplied.
The only check it passes is against buf_len, the number of bytes the DMA
delivered, which says nothing about the destination.  report_buf holds
HIDSPI_OUTPUT_REPORT_SIZE(max(max_output_len, max_input_len)), 68 bytes
for a controller reporting 64 for both, while the copy is bounded only by
the 4K DMA packet.

The REPORT_DESCRIPTOR_RESPONSE case a few lines up validates against the
size of its own destination.  Do the same here and let the waiter in
quickspi_get_report() time out, as the other malformed-frame checks do.

Fixes: 9d8d51735a3a ("HID: intel-thc-hid: intel-quickspi: Add HIDSPI protocol implementation")
Cc: [email protected]
Assisted-by: Claude:claude-opus-5
Signed-off-by: HyeongJun An <[email protected]>
---
This needs commit a59cf84441f9 ("HID: intel-thc-hid: intel-quickspi:
validate report size before copy") for qsdev->report_buf_size, which is in
hid.git for-next but not mainline yet.  Same Fixes: tag, so a stable
backport wants the two in that order.

 .../intel-thc-hid/intel-quickspi/quickspi-protocol.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
index 847c5ec55569..7d34cc22a11a 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
@@ -161,6 +161,7 @@ void quickspi_handle_input_data(struct quickspi_device *qsdev, u32 buf_len)
 	struct input_report_body *input_body;
 	u8 *input_report;
 	u32 input_len;
+	u32 report_len;
 	int ret = 0;
 
 	input_body = (struct input_report_body *)qsdev->input_buf;
@@ -210,10 +211,17 @@ void quickspi_handle_input_data(struct quickspi_device *qsdev, u32 buf_len)
 
 	case GET_FEATURE_RESPONSE:
 	case GET_INPUT_REPORT_RESPONSE:
-		qsdev->report_len = sizeof(body_hdr->content_id) + input_len;
+		report_len = sizeof(body_hdr->content_id) + input_len;
+		if (report_len > qsdev->report_buf_size) {
+			dev_err_once(qsdev->dev, "Get report response too big: %u\n",
+				     report_len);
+			return;
+		}
+
+		qsdev->report_len = report_len;
 		input_report = input_body->content - sizeof(body_hdr->content_id);
 
-		memcpy(qsdev->report_buf, input_report, qsdev->report_len);
+		memcpy(qsdev->report_buf, input_report, report_len);
 
 		qsdev->get_report_cmpl = true;
 		wake_up_interruptible(&qsdev->get_report_cmpl_wq);
-- 
2.43.0