[PATCH] HID: intel-thc-hid: intel-quickspi: bound GET_REPORT response to the caller buffer

quickspi_hid_raw_request() receives the caller's buffer length in len, but
quickspi_get_report() never sees it and copies the whole device-supplied
response into buf regardless:

    memcpy(buf, qsdev->report_buf, qsdev->report_len);

qsdev->report_len comes from the input report the touch controller returns,
while buf is sized to whatever the caller asked hidraw for through
HIDIOCGFEATURE or HIDIOCGINPUT.  A response larger than that overflows buf
with device-controlled content.

The intel-quicki2c sibling already passes the caller length down to
quicki2c_get_report() and validates the response against it before the
copy.  Do the same here.

Fixes: 4138f21115ae ("HID: intel-thc-hid: intel-quickspi: Complete THC QuickSPI driver")
Suggested-by: Sashiko AI <[email protected]>
Cc: [email protected]
Assisted-by: Claude:claude-opus-5
Signed-off-by: HyeongJun An <[email protected]>
---
 drivers/hid/intel-thc-hid/intel-quickspi/quickspi-hid.c  | 2 +-
 .../hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c | 9 ++++++++-
 .../hid/intel-thc-hid/intel-quickspi/quickspi-protocol.h | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-hid.c b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-hid.c
index 91d5807b4a83..a60a0a7f16aa 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-hid.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-hid.c
@@ -61,7 +61,7 @@ static int quickspi_hid_raw_request(struct hid_device *hid,
 
 	switch (reqtype) {
 	case HID_REQ_GET_REPORT:
-		ret = quickspi_get_report(qsdev, rtype, reportnum, buf);
+		ret = quickspi_get_report(qsdev, rtype, reportnum, buf, len);
 		break;
 	case HID_REQ_SET_REPORT:
 		ret = quickspi_set_report(qsdev, rtype, reportnum, buf, len);
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 cb19057f1191..9c4fce09729d 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
@@ -342,7 +342,8 @@ int reset_tic(struct quickspi_device *qsdev)
 }
 
 int quickspi_get_report(struct quickspi_device *qsdev,
-			u8 report_type, unsigned int report_id, void *buf)
+			u8 report_type, unsigned int report_id, void *buf,
+			u32 buf_len)
 {
 	int rep_type;
 	int ret;
@@ -372,6 +373,12 @@ int quickspi_get_report(struct quickspi_device *qsdev,
 	}
 	qsdev->get_report_cmpl = false;
 
+	if (qsdev->report_len > buf_len) {
+		dev_err_once(qsdev->dev, "Get report response too big, %u vs %u\n",
+			     qsdev->report_len, buf_len);
+		return -EINVAL;
+	}
+
 	memcpy(buf, qsdev->report_buf, qsdev->report_len);
 
 	return qsdev->report_len;
diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.h b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.h
index 775e29c1ed13..8a2338bee808 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.h
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.h
@@ -12,7 +12,7 @@ struct quickspi_device;
 
 void quickspi_handle_input_data(struct quickspi_device *qsdev, u32 buf_len);
 int quickspi_get_report(struct quickspi_device *qsdev, u8 report_type,
-			unsigned int report_id, void *buf);
+			unsigned int report_id, void *buf, u32 buf_len);
 int quickspi_set_report(struct quickspi_device *qsdev, u8 report_type,
 			unsigned int report_id, void *buf, u32 buf_len);
 int quickspi_get_report_descriptor(struct quickspi_device *qsdev);
-- 
2.43.0