linux-kernel - Re: [PATCH 1/1] media: v4l: Don't turn on privacy LED if streamon fails

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

Message-ID: <ZhZ5dZ68CM5IBMtW@kekkonen.localdomain>
Date: Wed, 10 Apr 2024 11:35:17 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: linux-media@...r.kernel.org, tomi.valkeinen@...asonboard.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Umang Jain <umang.jain@...asonboard.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] media: v4l: Don't turn on privacy LED if streamon
 fails

On Wed, Apr 10, 2024 at 11:31:48AM +0000, Sakari Ailus wrote:
> Hi Hans,
> 
> Thanks for the review.
> 
> On Wed, Apr 10, 2024 at 12:12:33PM +0200, Hans de Goede wrote:
> > Hi Sakari,
> > 
> > Thank you for fixing this.
> > 
> > On 4/10/24 12:03 PM, Sakari Ailus wrote:
> > > Turn on the privacy LED only if streamon succeeds. This can be done after
> > > enabling streaming on the sensor.
> > > 
> > > Fixes: b6e10ff6c23d ("media: v4l2-core: Make the v4l2-core code enable/disable the privacy LED if present")
> > > Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> > > ---
> > >  drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++---------
> > >  1 file changed, 10 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > > index 4c6198c48dd6..acb7c3003ab6 100644
> > > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > > @@ -412,15 +412,6 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
> > >  	if (WARN_ON(!!sd->enabled_streams == !!enable))
> > >  		return 0;
> > >  
> > > -#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> > > -	if (!IS_ERR_OR_NULL(sd->privacy_led)) {
> > > -		if (enable)
> > > -			led_set_brightness(sd->privacy_led,
> > > -					   sd->privacy_led->max_brightness);
> > > -		else
> > > -			led_set_brightness(sd->privacy_led, 0);
> > > -	}
> > > -#endif
> > >  	ret = sd->ops->video->s_stream(sd, enable);
> > >  
> > >  	if (!enable && ret < 0) {
> > > @@ -431,6 +422,16 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
> > >  	if (!ret)
> > >  		sd->enabled_streams = enable ? BIT(0) : 0;
> > >  
> > > +#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> > > +	if (!IS_ERR_OR_NULL(sd->privacy_led) && !(enable && ret < 0)) {
> > 
> > There already is a:
> > 
> > 	if (!enable && ret < 0)
> > 		ret = 0;
> > 
> > block above to ignore stream-off errors, so you can just test for:
> > 
> > 	if (!ret && !IS_ERR_OR_NULL(sd->privacy_led)) {
> > 		...
> > 	}
> > 
> > And then you can move the whole block to inside the existing:
> > 
> > 	if (!ret)
> > 		sd->enabled_streams = enable ? BIT(0) : 0;
> > 
> > block, so you get something like this:
> > 
> > 	if (!ret) {
> > 		sd->enabled_streams = enable ? BIT(0) : 0;
> > #if IS_REACHABLE(CONFIG_LEDS_CLASS)
> > 		if (!IS_ERR_OR_NULL(sd->privacy_led)) {
> > 			if (enable)
> > 				led_set_brightness(sd->privacy_led,
> > 						   sd->privacy_led->max_brightness);
> > 			else
> > 				led_set_brightness(sd->privacy_led, 0);
> > 		}
> > #endif
> > 	}
> 
> Seems reasonable, I'll send v2.

I was a bit too fast to hit y. ret will be non-zero if streamon fails
(enable non-zero), in which case the LED needs to be turned off. So you
can't have !ret condition for all LED control.

> 
> > 
> > Which then cleans up nicely by Tomi's patch
> > introducing the privacy LED helper functions,
> > to something like this:
> > 
> > 	if (!ret {
> > 		if (enable) {
> > 			sd->enabled_streams = BIT(0);
> > 			v4l2_subdev_enable_privacy_led(sd);
> > 		} else {
> > 			sd->enabled_streams = 0;
> > 			v4l2_subdev_disable_privacy_led(sd);
> > 		}
> > 	}
> > 
> 

-- 
Sakari Ailus