[PATCH v2 4/4] HID: wacom: use __free(kfree) to clean up temporary buffers

[Benjamin Tissoires <bentiss@kernel.org>]

This simplifies error handling and protects against memory leaks.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
 drivers/hid/wacom_sys.c | 40 +++++++++++++---------------------------
 1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index a32320b351e3..adb31f54e524 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -70,11 +70,10 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 {
 	while (!kfifo_is_empty(fifo)) {
 		int size = kfifo_peek_len(fifo);
-		u8 *buf;
 		unsigned int count;
 		int err;
 
-		buf = kzalloc(size, GFP_KERNEL);
+		u8 *buf __free(kfree) = kzalloc(size, GFP_KERNEL);
 		if (!buf) {
 			kfifo_skip(fifo);
 			continue;
@@ -87,7 +86,6 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 			// to flush seems reasonable enough, however.
 			hid_warn(hdev, "%s: removed fifo entry with unexpected size\n",
 				 __func__);
-			kfree(buf);
 			continue;
 		}
 		err = hid_report_raw_event(hdev, HID_INPUT_REPORT, buf, size, size, false);
@@ -95,8 +93,6 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 			hid_warn(hdev, "%s: unable to flush event due to error %d\n",
 				 __func__, err);
 		}
-
-		kfree(buf);
 	}
 }
 
@@ -311,7 +307,6 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 	struct wacom_features *features = &wacom->wacom_wac.features;
 	struct hid_data *hid_data = &wacom->wacom_wac.hid_data;
 	unsigned int equivalent_usage = wacom_equivalent_usage(usage->hid);
-	u8 *data;
 	int ret;
 	u32 n;
 
@@ -325,10 +320,11 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 		/* leave touch_max as is if predefined */
 		if (!features->touch_max) {
 			/* read manually */
-			n = hid_report_len(field->report);
-			data = hid_alloc_report_buf(field->report, GFP_KERNEL);
+			u8 *data __free(kfree) = hid_alloc_report_buf(field->report, GFP_KERNEL);
+
 			if (!data)
 				break;
+			n = hid_report_len(field->report);
 			data[0] = field->report->id;
 			ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
 					       data, n, WAC_CMD_RETRIES);
@@ -344,7 +340,6 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 					 "defaulting to %d\n",
 					  features->touch_max);
 			}
-			kfree(data);
 		}
 		break;
 	case HID_DG_INPUTMODE:
@@ -386,10 +381,11 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 	case WACOM_HID_WD_OFFSETRIGHT:
 	case WACOM_HID_WD_OFFSETBOTTOM:
 		/* read manually */
-		n = hid_report_len(field->report);
-		data = hid_alloc_report_buf(field->report, GFP_KERNEL);
+		u8 *data __free(kfree) = hid_alloc_report_buf(field->report, GFP_KERNEL);
+
 		if (!data)
 			break;
+		n = hid_report_len(field->report);
 		data[0] = field->report->id;
 		ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
 					data, n, WAC_CMD_RETRIES);
@@ -400,7 +396,6 @@ static void wacom_feature_mapping(struct hid_device *hdev,
 			hid_warn(hdev, "%s: could not retrieve sensor offsets\n",
 				 __func__);
 		}
-		kfree(data);
 		break;
 	}
 }
@@ -581,7 +576,6 @@ static int wacom_hid_set_device_mode(struct hid_device *hdev)
 static int wacom_set_device_mode(struct hid_device *hdev,
 				 struct wacom_wac *wacom_wac)
 {
-	u8 *rep_data;
 	struct hid_report *r;
 	struct hid_report_enum *re;
 	u32 length;
@@ -595,7 +589,7 @@ static int wacom_set_device_mode(struct hid_device *hdev,
 	if (!r)
 		return -EINVAL;
 
-	rep_data = hid_alloc_report_buf(r, GFP_KERNEL);
+	u8 *rep_data __free(kfree) = hid_alloc_report_buf(r, GFP_KERNEL);
 	if (!rep_data)
 		return -ENOMEM;
 
@@ -614,8 +608,6 @@ static int wacom_set_device_mode(struct hid_device *hdev,
 		 rep_data[1] != wacom_wac->mode_report &&
 		 limit++ < WAC_MSG_RETRIES);
 
-	kfree(rep_data);
-
 	return error < 0 ? error : 0;
 }
 
@@ -921,7 +913,6 @@ static int wacom_add_shared_data(struct hid_device *hdev)
 
 static int wacom_led_control(struct wacom *wacom)
 {
-	unsigned char *buf;
 	int retval;
 	unsigned char report_id = WAC_CMD_LED_CONTROL;
 	int buf_size = 9;
@@ -940,7 +931,8 @@ static int wacom_led_control(struct wacom *wacom)
 		report_id = WAC_CMD_WL_INTUOSP2;
 		buf_size = 51;
 	}
-	buf = kzalloc(buf_size, GFP_KERNEL);
+
+	unsigned char *buf __free(kfree) = kzalloc(buf_size, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -996,7 +988,6 @@ static int wacom_led_control(struct wacom *wacom)
 
 	retval = wacom_set_report(wacom->hdev, HID_FEATURE_REPORT, buf, buf_size,
 				  WAC_CMD_RETRIES);
-	kfree(buf);
 
 	return retval;
 }
@@ -1004,11 +995,10 @@ static int wacom_led_control(struct wacom *wacom)
 static int wacom_led_putimage(struct wacom *wacom, int button_id, u8 xfer_id,
 		const unsigned len, const void *img)
 {
-	unsigned char *buf;
 	int i, retval;
 	const unsigned chunk_len = len / 4; /* 4 chunks are needed to be sent */
 
-	buf = kzalloc(chunk_len + 3 , GFP_KERNEL);
+	unsigned char *buf __free(kfree) = kzalloc(chunk_len + 3, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -1018,7 +1008,7 @@ static int wacom_led_putimage(struct wacom *wacom, int button_id, u8 xfer_id,
 	retval = wacom_set_report(wacom->hdev, HID_FEATURE_REPORT, buf, 2,
 				  WAC_CMD_RETRIES);
 	if (retval < 0)
-		goto out;
+		return retval;
 
 	buf[0] = xfer_id;
 	buf[1] = button_id & 0x07;
@@ -1038,8 +1028,6 @@ static int wacom_led_putimage(struct wacom *wacom, int button_id, u8 xfer_id,
 	wacom_set_report(wacom->hdev, HID_FEATURE_REPORT, buf, 2,
 			 WAC_CMD_RETRIES);
 
-out:
-	kfree(buf);
 	return retval;
 }
 
@@ -1948,10 +1936,9 @@ static int wacom_remote_create_attr_group(struct wacom *wacom, __u32 serial,
 static int wacom_cmd_unpair_remote(struct wacom *wacom, unsigned char selector)
 {
 	const size_t buf_size = 2;
-	unsigned char *buf;
 	int retval;
 
-	buf = kzalloc(buf_size, GFP_KERNEL);
+	unsigned char *buf __free(kfree) = kzalloc(buf_size, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -1960,7 +1947,6 @@ static int wacom_cmd_unpair_remote(struct wacom *wacom, unsigned char selector)
 
 	retval = wacom_set_report(wacom->hdev, HID_OUTPUT_REPORT, buf,
 				  buf_size, WAC_CMD_RETRIES);
-	kfree(buf);
 
 	return retval;
 }

-- 
2.53.0