linux-kernel - Re: [PATCH v2 RESEND 2/2] Input: psmouse - Replace flush_workqueue() with disable_delayed_work

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <67e94e29.46daa.19b31d9f861.Coremail.duoming@zju.edu.cn>
Date: Thu, 18 Dec 2025 22:25:27 +0800 (GMT+08:00)
From: duoming@....edu.cn
To: "Dmitry Torokhov" <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	pali@...nel.org, kuba@...nel.org, alexander.deucher@....com,
	akpm@...ux-foundation.org, johannes.berg@...el.com,
	pkshih@...ltek.com, hverkuil+cisco@...nel.org,
	andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
	mingo@...nel.org
Subject: Re: [PATCH v2 RESEND 2/2] Input: psmouse - Replace
 flush_workqueue() with disable_delayed_work_sync()

On Wed, 17 Dec 2025 22:58:33 -0800 Dmitry Torokhov wrote:
> > > > The original code uses flush_workqueue() in psmouse_disconnect() to
> > > > ensure the completion of both resync_work and dev3_register_work.
> > > > Given that alps_disconnect() already uses disable_delayed_work_sync()
> > > > to cancel dev3_register_work, replacing flush_workqueue() with
> > > > disable_delayed_work_sync(&psmouse->resync_work) is more robust
> > > > and efficient.
> > > > 
> > > > Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> > > > ---
> > > > Changes in v2:
> > > >   - focus on the robustness and efficiency improvements of disable_delayed_work_sync(), not on the UAF aspect.
> > > > 
> > > >  drivers/input/mouse/psmouse-base.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
> > > > index 77ea7da3b1c..eb41c553e80 100644
> > > > --- a/drivers/input/mouse/psmouse-base.c
> > > > +++ b/drivers/input/mouse/psmouse-base.c
> > > > @@ -1484,7 +1484,7 @@ static void psmouse_disconnect(struct serio *serio)
> > > >  
> > > >  	/* make sure we don't have a resync in progress */
> > > >  	mutex_unlock(&psmouse_mutex);
> > > > -	flush_workqueue(kpsmoused_wq);
> > > > +	disable_delayed_work_sync(&psmouse->resync_work);
> > > 
> > > Before we replace flush_workqueue() with disable_delayed_work_sync() we
> > > need to also add disable_delayed_work_sync() to
> > > drivers/input/mouse/hgpk.c that also queues work to psmouse workqueue
> > > and relies on flushing it when disconnecting.
> > 
> > The delayed work item recalib_wq could never be scheduled due to the 
> > touchpad driver only supports mouse mode and the hgpk_init() function
> > remains disabled.
> 
> What do you mean? If you enable OLPC support the option to enable hgpk
> protocol driver should become available, right?

The hgpk_init() function is never called by any other function in the
kernel and is therefore dead code. Since the delayed work item recalib_wq
is initialized within this function, it is consequently never scheduled
during runtime.

Best regards,
Duoming Zhou