linux-kernel - Re: [PATCH] driver: core: Fix list corruption after device

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Date:   Tue, 8 Dec 2020 20:20:04 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] driver: core: Fix list corruption after device_del()

On Tue, Dec 8, 2020 at 8:03 PM Takashi Iwai <tiwai@...e.de> wrote:
>
> The device_links_purge() function (called from device_del()) tries to
> remove the links.needs_suppliers list entry, but it's using
> list_del(), hence it doesn't initialize after the removal.  This is OK
> for normal cases where device_del() is called via device_destroy().
> However, it's not guaranteed that the device object will be really
> deleted soon after device_del().  In a minor case like HD-audio codec
> reconfiguration that re-initializes the device after device_del(), it
> may lead to a crash by the corrupted list entry.
>
> As a simple fix, replace list_del() with list_del_init() in order to
> make the list intact after the device_del() call.
>
> Fixes: e2ae9bcc4aaa ("driver core: Add support for linking devices during device addition")
> Cc: <stable@...r.kernel.org>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209207
> Signed-off-by: Takashi Iwai <tiwai@...e.de>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/base/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index d661ada1518f..e8cb66093f21 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1386,7 +1386,7 @@ static void device_links_purge(struct device *dev)
>                 return;
>
>         mutex_lock(&wfs_lock);
> -       list_del(&dev->links.needs_suppliers);
> +       list_del_init(&dev->links.needs_suppliers);
>         mutex_unlock(&wfs_lock);
>
>         /*
> --
> 2.26.2
>