Input: ims-pcu - add response length checks

The driver processes response data from device buffers without verifying
that the device actually sent enough data. This can lead to
out-of-bounds reads or processing stale data.

Add checks for the expected response length before accessing the
buffers.

Fixes: 628329d52474 ("Input: add IMS Passenger Control Unit driver")
Cc: stable@vger.kernel.org
Reported-by: Sashiko bot <sashiko-bot@kernel.org>
Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 81 insertions, 6 deletions

diff --git a/drivers/input/misc/ims-pcu.c b/drivers/input/misc/ims-pcu.c
index 371c605efcf4..a730cc2690d5 100644
--- a/drivers/input/misc/ims-pcu.c
+++ b/drivers/input/misc/ims-pcu.c
@@ -407,7 +407,16 @@ static void ims_pcu_destroy_gamepad(struct ims_pcu *pcu)
 
 static void ims_pcu_report_events(struct ims_pcu *pcu)
 {
-	u32 data = get_unaligned_be32(&pcu->read_buf[3]);
+	u32 data;
+
+	/* 6-axis setting (1 byte) + button data + checksum */
+	if (pcu->read_pos < IMS_PCU_DATA_OFFSET + 1 + sizeof(data) + 1) {
+		dev_warn(pcu->dev, "Short buttons report: %d bytes\n",
+			 pcu->read_pos);
+		return;
+	}
+
+	data = get_unaligned_be32(&pcu->read_buf[IMS_PCU_DATA_OFFSET + 1]);
 
 	ims_pcu_buttons_report(pcu, data & ~IMS_PCU_GAMEPAD_MASK);
 	if (pcu->gamepad)
@@ -687,11 +696,19 @@ static int __ims_pcu_execute_bl_command(struct ims_pcu *pcu,
 		return error;
 	}
 
-	if (expected_response && pcu->cmd_buf[2] != expected_response) {
-		dev_err(pcu->dev,
-			"Unexpected response from bootloader: 0x%02x, wanted 0x%02x\n",
-			pcu->cmd_buf[2], expected_response);
-		return -EINVAL;
+	if (expected_response) {
+		if (pcu->cmd_buf_len < 3) {
+			dev_err(pcu->dev, "Short response from bootloader: %d bytes\n",
+				pcu->cmd_buf_len);
+			return -EIO;
+		}
+
+		if (pcu->cmd_buf[2] != expected_response) {
+			dev_err(pcu->dev,
+				"Unexpected response from bootloader: 0x%02x, wanted 0x%02x\n",
+				pcu->cmd_buf[2], expected_response);
+			return -EINVAL;
+		}
 	}
 
 	return 0;
@@ -719,6 +736,12 @@ static int ims_pcu_get_info(struct ims_pcu *pcu)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + IMS_PCU_SET_INFO_SIZE + 1) {
+		dev_err(pcu->dev, "Short GET_INFO response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	memcpy(pcu->part_number,
 	       &pcu->cmd_buf[IMS_PCU_INFO_PART_OFFSET],
 	       sizeof(pcu->part_number));
@@ -816,6 +839,12 @@ static int ims_pcu_verify_block(struct ims_pcu *pcu,
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_BL_DATA_OFFSET + sizeof(*fragment) + len + 1) {
+		dev_err(pcu->dev, "Short READ_APP response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	fragment = (void *)&pcu->cmd_buf[IMS_PCU_BL_DATA_OFFSET];
 	if (get_unaligned_le32(&fragment->addr) != addr ||
 	    fragment->len != len) {
@@ -1009,6 +1038,10 @@ ims_pcu_backlight_get_brightness(struct led_classdev *cdev)
 			 error);
 		/* Assume the LED is OFF */
 		brightness = LED_OFF;
+	} else if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 2 + 1) {
+		dev_err(pcu->dev, "Short GET_BRIGHTNESS response: %d bytes\n",
+			pcu->cmd_buf_len);
+		brightness = LED_OFF;
 	} else {
 		brightness =
 			get_unaligned_le16(&pcu->cmd_buf[IMS_PCU_DATA_OFFSET]);
@@ -1287,6 +1320,12 @@ static int ims_pcu_read_ofn_config(struct ims_pcu *pcu, u8 addr, u8 *data)
 	if (error)
 		return error;
 
+	if (pcu->cmd_buf_len < OFN_REG_RESULT_OFFSET + 2 + 1) {
+		dev_err(pcu->dev, "Short OFN_GET_CONFIG response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	result = (s16)get_unaligned_le16(pcu->cmd_buf + OFN_REG_RESULT_OFFSET);
 	if (result < 0)
 		return -EIO;
@@ -1307,6 +1346,12 @@ static int ims_pcu_write_ofn_config(struct ims_pcu *pcu, u8 addr, u8 data)
 	if (error)
 		return error;
 
+	if (pcu->cmd_buf_len < OFN_REG_RESULT_OFFSET + 2 + 1) {
+		dev_err(pcu->dev, "Short OFN_SET_CONFIG response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	result = (s16)get_unaligned_le16(pcu->cmd_buf + OFN_REG_RESULT_OFFSET);
 	if (result < 0)
 		return -EIO;
@@ -1850,6 +1895,12 @@ static int ims_pcu_get_device_info(struct ims_pcu *pcu)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 6 + 1) {
+		dev_err(pcu->dev, "Short GET_FW_VERSION response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	snprintf(pcu->fw_version, sizeof(pcu->fw_version),
 		 "%02d%02d%02d%02d.%c%c",
 		 pcu->cmd_buf[2], pcu->cmd_buf[3], pcu->cmd_buf[4], pcu->cmd_buf[5],
@@ -1862,6 +1913,12 @@ static int ims_pcu_get_device_info(struct ims_pcu *pcu)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 6 + 1) {
+		dev_err(pcu->dev, "Short GET_BL_VERSION response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	snprintf(pcu->bl_version, sizeof(pcu->bl_version),
 		 "%02d%02d%02d%02d.%c%c",
 		 pcu->cmd_buf[2], pcu->cmd_buf[3], pcu->cmd_buf[4], pcu->cmd_buf[5],
@@ -1874,6 +1931,12 @@ static int ims_pcu_get_device_info(struct ims_pcu *pcu)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 1 + 1) {
+		dev_err(pcu->dev, "Short RESET_REASON response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	snprintf(pcu->reset_reason, sizeof(pcu->reset_reason),
 		 "%02x", pcu->cmd_buf[IMS_PCU_DATA_OFFSET]);
 
@@ -1900,6 +1963,12 @@ static int ims_pcu_identify_type(struct ims_pcu *pcu, u8 *device_id)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 1 + 1) {
+		dev_err(pcu->dev, "Short GET_DEVICE_ID response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	*device_id = pcu->cmd_buf[IMS_PCU_DATA_OFFSET];
 	dev_dbg(pcu->dev, "Detected device ID: %d\n", *device_id);
 
@@ -1991,6 +2060,12 @@ static int ims_pcu_init_bootloader_mode(struct ims_pcu *pcu)
 		return error;
 	}
 
+	if (pcu->cmd_buf_len < IMS_PCU_DATA_OFFSET + 15 + 4 + 1) {
+		dev_err(pcu->dev, "Short QUERY_DEVICE response: %d bytes\n",
+			pcu->cmd_buf_len);
+		return -EIO;
+	}
+
 	pcu->fw_start_addr =
 		get_unaligned_le32(&pcu->cmd_buf[IMS_PCU_DATA_OFFSET + 11]);
 	pcu->fw_end_addr =