wwan_hwsim: fix possible memory leak in wwan_hwsim_dev_new()

Inject fault while probing module, if device_register() fails,
but the refcount of kobject is not decreased to 0, the name
allocated in dev_set_name() is leaked. Fix this by calling
put_device(), so that name can be freed in callback function
kobject_cleanup().

unreferenced object 0xffff88810152ad20 (size 8):
  comm "modprobe", pid 252, jiffies 4294849206 (age 22.713s)
  hex dump (first 8 bytes):
    68 77 73 69 6d 30 00 ff                          hwsim0..
  backtrace:
    [<000000009c3504ed>] __kmalloc_node_track_caller+0x44/0x1b0
    [<00000000c0228a5e>] kvasprintf+0xb5/0x140
    [<00000000cff8c21f>] kvasprintf_const+0x55/0x180
    [<0000000055a1e073>] kobject_set_name_vargs+0x56/0x150
    [<000000000a80b139>] dev_set_name+0xab/0xe0

Fixes: f36a111 ("wwan_hwsim: WWAN device simulator")
Signed-off-by: Yang Yingliang <[email protected]>
Reviewed-by: Loic Poulain <[email protected]>
Acked-by: Sergey Ryazanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Yang Yingliang

drivers/net/wwan/wwan_hwsim.c

@@ -311,7 +311,7 @@ static struct wwan_hwsim_dev *wwan_hwsim_dev_new(void)
 	return ERR_PTR(err);
 
 err_free_dev:
-	kfree(dev);
+	put_device(&dev->dev);
 
 	return ERR_PTR(err);
 }