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

[Chen Zhongjin]

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.

Fixes: fb257897bf20 ("ASoC: Work around allmodconfig failure")
Signed-off-by: Chen Zhongjin <chenzhongjin at huawei.com>
---
 sound/soc/soc-core.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 12a82f5a3ff6..a409fbed8f34 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3477,10 +3477,23 @@ EXPORT_SYMBOL_GPL(snd_soc_of_get_dai_link_cpus);
 
 static int __init snd_soc_init(void)
 {
+	int ret;
+
 	snd_soc_debugfs_init();
-	snd_soc_util_init();
+	ret = snd_soc_util_init();
+	if (ret)
+		goto err_util_init;
 
-	return platform_driver_register(&soc_driver);
+	ret = platform_driver_register(&soc_driver);
+	if (ret)
+		goto err_register;
+	return 0;
+
+err_register:
+	snd_soc_util_exit();
+err_util_init:
+	snd_soc_debugfs_exit();
+	return ret;
 }
 module_init(snd_soc_init);
 
-- 
2.17.1