[PATCH v2] HID: intel-thc-hid: intel-quickspi: validate GET REPORT response size

[Even Xu <even.xu@intel.com>]

From: HyeongJun An <sammiee5311@gmail.com>

quickspi_handle_input_data() copies GET_FEATURE and
GET_INPUT_REPORT responses into qsdev->report_buf. The response length
is derived from data supplied by the controller, but was not checked
against the destination buffer size.

Adjust qsdev->report_buf_size to store the data length of report buffer,
reject responses that exceed it before copying. This prevents an
oversized response from overflowing report_buf. The rejected response
does not complete the GET REPORT request, so quickspi_get_report()
follows its existing timeout path.

Fixes: 9d8d51735a3a ("HID: intel-thc-hid: intel-quickspi: Add HIDSPI protocol implementation")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Signed-off-by: Even Xu <even.xu@intel.com>
Tested-by: Rui Zhang <rui1.zhang@intel.com>
---
Change log:
V2:
 - Rebased on top of latest mainline kernel
 - Adjust qsdev->report_buf_size to store the data length of report buffer

---
 .../intel-thc-hid/intel-quickspi/pci-quickspi.c  | 16 ++++++++--------
 .../intel-thc-hid/intel-quickspi/quickspi-dev.h  |  1 +
 .../intel-quickspi/quickspi-protocol.c           | 12 ++++++++++--
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c b/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
index 53023e30cf8d..d0aa66a8a4b4 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/pci-quickspi.c
@@ -562,17 +562,17 @@ static int quickspi_alloc_report_buf(struct quickspi_device *qsdev)
 	max_report_len = max(le16_to_cpu(qsdev->dev_desc.max_output_len),
 			     le16_to_cpu(qsdev->dev_desc.max_input_len));
 
-	/*
-	 * write_cmd_to_txdma() writes the output report header ahead of the
-	 * content in this buffer, so it has to hold both.
-	 */
-	qsdev->report_buf_size = HIDSPI_OUTPUT_REPORT_SIZE(max_report_len);
-
-	qsdev->report_buf = devm_kzalloc(qsdev->dev, qsdev->report_buf_size,
-					 GFP_KERNEL);
+	qsdev->report_buf = devm_kzalloc(qsdev->dev,
+					 HIDSPI_OUTPUT_REPORT_SIZE(max_report_len), GFP_KERNEL);
 	if (!qsdev->report_buf)
 		return -ENOMEM;
 
+	/*
+	 * Store the max data length of this report buffer, then compare it with output/input
+	 * packet content when write or read into this report buffer to avoid buffer overflow.
+	 */
+	qsdev->report_buf_size = max_report_len;
+
 	return 0;
 }
 
diff --git a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
index fe51ff51d8c0..4362ac568bda 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-dev.h
@@ -115,6 +115,7 @@ struct acpi_device;
  * @input_buf: store a copy of latest input report data
  * @input_len: the data size of the input report buffer
  * @report_buf: store a copy of latest input/output report packet from set/get feature
+ * @report_buf_size: the data size of input/output buffer
  * @report_len: the length of input/output report packet
  * @reset_ack_wq: workqueue for waiting reset response from device
  * @reset_ack: indicate reset response received or not
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 0df33c44fbff..5de25c36a1e4 100644
--- a/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
+++ b/drivers/hid/intel-thc-hid/intel-quickspi/quickspi-protocol.c
@@ -30,7 +30,7 @@ static int write_cmd_to_txdma(struct quickspi_device *qsdev,
 
 	write_buf = (struct output_report *)qsdev->report_buf;
 
-	if (HIDSPI_OUTPUT_REPORT_SIZE(report_buf_len) > qsdev->report_buf_size)
+	if (report_buf_len > qsdev->report_buf_size)
 		return -EINVAL;
 
 	write_buf->output_hdr.report_type = report_type;
@@ -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;
@@ -210,7 +211,14 @@ 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);
-- 
2.43.0