[PATCH] HID: multitouch: prevent memleak with the allocated name

[Andy Shevchenko <andy.shevchenko@gmail.com>]

mt_free_input_name() was never called during .remove(): hid_hw_stop()
removes the hid_input items in hdev->inputs, and so the list is
therefore empty after the call. In the end, we never free the special
names that has been allocated during .probe().

We switch to devm_kzalloc that manages resources when driver is removed.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reported-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
---
 drivers/hid/hid-multitouch.c |   37 +++++++++++++------------------------
 1 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index d99b959..1f5876e 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -261,14 +261,6 @@ static struct mt_class mt_classes[] = {
 	{ }
 };
 
-static void mt_free_input_name(struct hid_input *hi)
-{
-	struct hid_device *hdev = hi->report->device;
-
-	if (hi->input->name != hdev->name)
-		kfree(hi->input->name);
-}
-
 static ssize_t mt_show_quirks(struct device *dev,
 			   struct device_attribute *attr,
 			   char *buf)
@@ -412,10 +404,12 @@ static void mt_pen_report(struct hid_device *hid, struct hid_report *report)
 static void mt_pen_input_configured(struct hid_device *hdev,
 					struct hid_input *hi)
 {
-	char *name = kzalloc(strlen(hi->input->name) + 5, GFP_KERNEL);
-	if (name) {
-		sprintf(name, "%s Pen", hi->input->name);
-		mt_free_input_name(hi);
+	char *name;
+
+	if (hdev->name) {
+		name = devm_kzalloc(&hdev->dev, strlen(hdev->name) + 5,
+							GFP_KERNEL);
+		sprintf(name, "%s Pen", hdev->name);
 		hi->input->name = name;
 	}
 
@@ -925,16 +919,18 @@ static void mt_post_parse(struct mt_device *td)
 static void mt_input_configured(struct hid_device *hdev, struct hid_input *hi)
 {
 	struct mt_device *td = hid_get_drvdata(hdev);
-	char *name = kstrdup(hdev->name, GFP_KERNEL);
-
-	if (name)
-		hi->input->name = name;
 
 	if (hi->report->id == td->mt_report_id)
 		mt_touch_input_configured(hdev, hi);
 
 	if (hi->report->id == td->pen_report_id)
 		mt_pen_input_configured(hdev, hi);
+
+	if (!hi->input->name) {
+		hi->input->name = devm_kzalloc(&hdev->dev,
+					strlen(hdev->name) + 1, GFP_KERNEL);
+		strcpy(hi->input->name, hdev->name);
+	}
 }
 
 static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
@@ -993,7 +989,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 	if (ret)
-		goto hid_fail;
+		goto fail;
 
 	ret = sysfs_create_group(&hdev->dev.kobj, &mt_attribute_group);
 
@@ -1005,9 +1001,6 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 	return 0;
 
-hid_fail:
-	list_for_each_entry(hi, &hdev->inputs, list)
-		mt_free_input_name(hi);
 fail:
 	kfree(td->fields);
 	kfree(td);
@@ -1037,14 +1030,10 @@ static int mt_resume(struct hid_device *hdev)
 static void mt_remove(struct hid_device *hdev)
 {
 	struct mt_device *td = hid_get_drvdata(hdev);
-	struct hid_input *hi;
 
 	sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
 	hid_hw_stop(hdev);
 
-	list_for_each_entry(hi, &hdev->inputs, list)
-		mt_free_input_name(hi);
-
 	kfree(td);
 	hid_set_drvdata(hdev, NULL);
 }
-- 
1.7.7.6