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From: Jaroslav Kysela <>
To: Dongliang Mu <>,,,,
Subject: Re: [PATCH v2] ALSA: control led: fix memory leak in snd_ctl_led_register
Date: Wed, 2 Jun 2021 08:47:04 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 02. 06. 21 5:41, Dongliang Mu wrote:
> The snd_ctl_led_sysfs_add and snd_ctl_led_sysfs_remove should contain
> the refcount operations in pair. However, snd_ctl_led_sysfs_remove fails
> to decrease the refcount to zero, which causes device_release never to
> be invoked. This leads to memory leak to some resources, like struct
> device_private. In addition, we also free some other similar memory
> leaks in snd_ctl_led_init/snd_ctl_led_exit.
> Fix this by replacing device_del to device_unregister
> in snd_ctl_led_sysfs_remove/snd_ctl_led_init/snd_ctl_led_exit.
> Note that, when CONFIG_DEBUG_KOBJECT_RELEASE is enabled, put_device will
> call kobject_release and delay the release of kobject, which will cause
> use-after-free when the memory backing the kobject is freed at once.
> Reported-by:
> Fixes: a135dfb5de1 ("ALSA: led control - add sysfs kcontrol LED marking layer")
> Signed-off-by: Dongliang Mu <>

Many thanks to you and Dan to cover this.

Revieved-by: Jaroslav Kysela <>

Jaroslav Kysela <>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

  parent reply	other threads:[~2021-06-02  6:47 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-02  3:41 Dongliang Mu
2021-06-02  6:35 ` Dan Carpenter
2021-06-02  6:35   ` Dan Carpenter
2021-06-02  6:47 ` Jaroslav Kysela [this message]
2021-06-02  6:59 ` Takashi Iwai
2021-06-02  6:59   ` Takashi Iwai

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