[PATCH 4.9 100/207] hwmon: Fix possible memleak in __hwmon_device_register()

[Greg Kroah-Hartman]

From: Yang Yingliang <yangyingliang@xxxxxxxxxx>

[ Upstream commit ada61aa0b1184a8fda1a89a340c7d6cc4e59aee5 ]

I got memory leak as follows when doing fault injection test:

unreferenced object 0xffff888102740438 (size 8):
  comm "27", pid 859, jiffies 4295031351 (age 143.992s)
  hex dump (first 8 bytes):
    68 77 6d 6f 6e 30 00 00                          hwmon0..
  backtrace:
    [<00000000544b5996>] __kmalloc_track_caller+0x1a6/0x300
    [<00000000df0d62b9>] kvasprintf+0xad/0x140
    [<00000000d3d2a3da>] kvasprintf_const+0x62/0x190
    [<000000005f8f0f29>] kobject_set_name_vargs+0x56/0x140
    [<00000000b739e4b9>] dev_set_name+0xb0/0xe0
    [<0000000095b69c25>] __hwmon_device_register+0xf19/0x1e50 [hwmon]
    [<00000000a7e65b52>] hwmon_device_register_with_info+0xcb/0x110 [hwmon]
    [<000000006f181e86>] devm_hwmon_device_register_with_info+0x85/0x100 [hwmon]
    [<0000000081bdc567>] tmp421_probe+0x2d2/0x465 [tmp421]
    [<00000000502cc3f8>] i2c_device_probe+0x4e1/0xbb0
    [<00000000f90bda3b>] really_probe+0x285/0xc30
    [<000000007eac7b77>] __driver_probe_device+0x35f/0x4f0
    [<000000004953d43d>] driver_probe_device+0x4f/0x140
    [<000000002ada2d41>] __device_attach_driver+0x24c/0x330
    [<00000000b3977977>] bus_for_each_drv+0x15d/0x1e0
    [<000000005bf2a8e3>] __device_attach+0x267/0x410

When device_register() returns an error, the name allocated in
dev_set_name() will be leaked, the put_device() should be used
instead of calling hwmon_dev_release() to give up the device
reference, then the name will be freed in kobject_cleanup().

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Fixes: bab2243ce189 ("hwmon: Introduce hwmon_device_register_with_groups")
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211012112758.2681084-1-yangyingliang@xxxxxxxxxx
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/hwmon/hwmon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index e0a1a118514f9..8b11d2fdf80ab 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -592,8 +592,10 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 	dev_set_drvdata(hdev, drvdata);
 	dev_set_name(hdev, HWMON_ID_FORMAT, id);
 	err = device_register(hdev);
-	if (err)
-		goto free_hwmon;
+	if (err) {
+		put_device(hdev);
+		goto ida_remove;
+	}
 
 	if (chip && chip->ops->is_visible && chip->ops->read &&
 	    chip->info[0]->type == hwmon_chip &&
-- 
2.33.0