driver core: fix resource leak in device_add()

In the Linux kernel, the following vulnerability has been resolved:

driver core: fix resource leak in device_add()

When calling kobject_add() failed in device_add(), it will call

cleanup_glue_dir() to free resource. But in kobject_add(),

dev->kobj.parent has been set to NULL. This will cause resource leak.

The process is as follows:

device_add()

get_device_parent()

class_dir_create_and_add()

kobject_add() //kobject_get()

...

dev->kobj.parent = kobj;

...

kobject_add() //failed, but set dev->kobj.parent = NULL

...

glue_dir = get_glue_dir(dev) //glue_dir = NULL, and goto

//"Error" label

...

cleanup_glue_dir() //becaues glue_dir is NULL, not call

//kobject_put()

The preceding problem may cause insmod mac80211_hwsim.ko to failed.

sysfs: cannot create duplicate filename '/devices/virtual/mac80211_hwsim'

Call Trace:

<TASK>

dump_stack_lvl+0x8e/0xd1

sysfs_warn_dup.cold+0x1c/0x29

sysfs_create_dir_ns+0x224/0x280

kobject_add_internal+0x2aa/0x880

kobject_add+0x135/0x1a0

get_device_parent+0x3d7/0x590

device_add+0x2aa/0x1cb0

device_create_groups_vargs+0x1eb/0x260

device_create+0xdc/0x110

mac80211_hwsim_new_radio+0x31e/0x4790 [mac80211_hwsim]

init_mac80211_hwsim+0x48d/0x1000 [mac80211_hwsim]

do_one_initcall+0x10f/0x630

do_init_module+0x19f/0x5e0

load_module+0x64b7/0x6eb0

__do_sys_finit_module+0x140/0x200

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

</TASK>

kobject_add_internal failed for mac80211_hwsim with -EEXIST, don't try to

register things with the same name in the same directory.