Re: [PATCH] driver: core: Fix list corruption after device_del()

From: Takashi Iwai <tiwai@suse.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] driver: core: Fix list corruption after device_del()
Date: Tue, 08 Dec 2020 21:25:32 +0100	[thread overview]
Message-ID: <s5hmtyoujsz.wl-tiwai@suse.de> (raw)
In-Reply-To: <X8/ZghuyCJfguuIE@kroah.com>

On Tue, 08 Dec 2020 20:52:34 +0100,
Greg Kroah-Hartman wrote:
> 
> On Tue, Dec 08, 2020 at 08:03:26PM +0100, Takashi Iwai 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@vger.kernel.org>
> > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209207
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> >  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);
> 
> Can this wait until 5.11-rc1 and then get backported, as it has been
> around for a while, or are you hitting this on 5.10-rc7 now and need
> this for 5.10-final?

This is rather a minor (but long-standing) issue, so no problem to
wait for 5.11.

thanks,

Takashi