Patch "ASoC: core: Fix use-after-free in snd_soc_exit()" has been added to the 4.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     asoc-core-fix-use-after-free-in-snd_soc_exit.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fa8c561bc36dcddffa537d0d1ce3997b63d949d4
Author: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
Date:   Fri Oct 28 11:16:03 2022 +0800

    ASoC: core: Fix use-after-free in snd_soc_exit()
    
    [ Upstream commit 6ec27c53886c8963729885bcf2dd996eba2767a7 ]
    
    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@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221028031603.59416-1-chenzhongjin@xxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 81c3aa167038..033253de5d4b 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3931,10 +3931,23 @@ EXPORT_SYMBOL_GPL(snd_soc_of_get_dai_link_codecs);
 
 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);