ASoC: core: Fix use-after-free in snd_soc_exit()

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

ASoC: core: Fix use-after-free in snd_soc_exit()

KASAN reports a use-after-free:

BUG: KASAN: use-after-free in device_del+0xb5b/0xc60

Read of size 8 at addr ffff888008655050 by task rmmod/387

CPU: 2 PID: 387 Comm: rmmod

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)

Call Trace:

<TASK>

dump_stack_lvl+0x79/0x9a

print_report+0x17f/0x47b

kasan_report+0xbb/0xf0

device_del+0xb5b/0xc60

platform_device_del.part.0+0x24/0x200

platform_device_unregister+0x2e/0x40

snd_soc_exit+0xa/0x22 [snd_soc_core]

__do_sys_delete_module.constprop.0+0x34f/0x5b0

do_syscall_64+0x3a/0x90

entry_SYSCALL_64_after_hwframe+0x63/0xcd

...

</TASK>

It's bacause in snd_soc_init(), snd_soc_util_init() is possble to fail,

but its ret is ignored, which makes soc_dummy_dev unregistered twice.

snd_soc_init()

snd_soc_util_init()

platform_device_register_simple(soc_dummy_dev)

platform_driver_register() # fail

platform_device_unregister(soc_dummy_dev)

platform_driver_register() # success

...

snd_soc_exit()

snd_soc_util_exit()

# soc_dummy_dev will be unregistered for second time

To fix it, handle error and stop snd_soc_init() when util_init() fail.

Also clean debugfs when util_init() or driver_register() fail.