[PATCH 2/2] hwmon: core: fix potential memory leak in *hwmon_device_register*

[Eduardo Valentin]

When registering a hwmon device with HWMON_C_REGISTER_TZ flag
in place, the hwmon subsystem will attempt to register the device
also with the thermal subsystem. When the of-thermal registration
fails, __hwmon_device_register jumps to ida_remove, leaving
the locally allocated hwdev pointer and also the hdev registered.

This patch fixes both issues by jumping to a new label that
will first unregister hdev and the fall into the kfree of hwdev
to finally remove the idas and propagate the error code.

Cc: Jean Delvare <jdelvare@xxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: linux-hwmon@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Eduardo Valentin <eduval@xxxxxxxxxx>
---
 drivers/hwmon/hwmon.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 6b3559f58b67..6f1194952189 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -637,7 +637,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 								hwdev, j);
 					if (err) {
 						device_unregister(hdev);
-						goto ida_remove;
+						goto device_unregister;
 					}
 				}
 			}
@@ -646,6 +646,8 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 
 	return hdev;
 
+device_unregister:
+	device_unregister(hdev);
 free_hwmon:
 	kfree(hwdev);
 ida_remove:
-- 
2.21.0