i2c: fix memleak in i2c_new_client_device()

Yang Yingliang reported a memleak:
===

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

unreferenced object 0xffff888014aec078 (size 8):
  comm "xrun", pid 356, jiffies 4294910619 (age 16.332s)
  hex dump (first 8 bytes):
    31 2d 30 30 31 63 00 00                          1-001c..
  backtrace:
    [<00000000eb56c0a9>] __kmalloc_track_caller+0x1a6/0x300
    [<000000000b220ea3>] kvasprintf+0xad/0x140
    [<00000000b83203e5>] kvasprintf_const+0x62/0x190
    [<000000002a5eab37>] kobject_set_name_vargs+0x56/0x140
    [<00000000300ac279>] dev_set_name+0xb0/0xe0
    [<00000000b66ebd6f>] i2c_new_client_device+0x7e4/0x9a0

If device_register() returns error in i2c_new_client_device(),
the name allocated by i2c_dev_set_name() need be freed. As
comment of device_register() says, it should use put_device()
to give up the reference in the error path.

===
I think this solution is less intrusive and more robust than he
originally proposed solutions, though.

Reported-by: Yang Yingliang <[email protected]>
Closes: http://patchwork.ozlabs.org/project/linux-i2c/patch/[email protected]/
Signed-off-by: Wolfram Sang <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Author: Wolfram Sang

drivers/i2c/i2c-core-base.c

@@ -931,8 +931,9 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
 struct i2c_client *
 i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
 {
-	struct i2c_client	*client;
-	int			status;
+	struct i2c_client *client;
+	bool need_put = false;
+	int status;
 
 	client = kzalloc(sizeof *client, GFP_KERNEL);
 	if (!client)
@@ -970,7 +971,6 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 	client->dev.fwnode = info->fwnode;
 
 	device_enable_async_suspend(&client->dev);
-	i2c_dev_set_name(adap, client, info);
 
 	if (info->swnode) {
 		status = device_add_software_node(&client->dev, info->swnode);
@@ -982,6 +982,7 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 		}
 	}
 
+	i2c_dev_set_name(adap, client, info);
 	status = device_register(&client->dev);
 	if (status)
 		goto out_remove_swnode;
@@ -993,14 +994,18 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 
 out_remove_swnode:
 	device_remove_software_node(&client->dev);
+	need_put = true;
 out_err_put_of_node:
 	of_node_put(info->of_node);
 out_err:
 	dev_err(&adap->dev,
 		"Failed to register i2c client %s at 0x%02x (%d)\n",
 		client->name, client->addr, status);
 out_err_silent:
-	kfree(client);
+	if (need_put)
+		put_device(&client->dev);
+	else
+		kfree(client);
 	return ERR_PTR(status);
 }
 EXPORT_SYMBOL_GPL(i2c_new_client_device);