linux-kernel - Re: [PATCH] media: uvcvideo: Return queued buffers on start

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: <20251113213733.GF9135@pendragon.ideasonboard.com>
Date: Thu, 13 Nov 2025 23:37:33 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Cc: Michal Pecio <michal.pecio@...il.com>, Hans de Goede <hansg@...nel.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...nel.org>,
	Ricardo Ribalda <ribalda@...omium.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: uvcvideo: Return queued buffers on
 start_streaming() failure

On Tue, Oct 21, 2025 at 12:47:23PM +0200, Ricardo Ribalda Delgado wrote:
> Hi Michal
> 
> It seems that the device was disconnected while doing streamon. That
> caused uvc_pm_get() to fail and exit without returning the buffers.
> 
> Your patch is not going to help to fix:
> xhci_hcd 0000:09:00.0: HC died; cleaning up
> usb 13-2: USB disconnect, device number 2
> 
> But it is fixing an issue. thanks :)
> 
> On Wed, Oct 15, 2025 at 1:36 PM Michal Pecio <michal.pecio@...il.com> wrote:
> >
> > Return buffers if streaming fails to start due to uvc_pm_get() error.
> >
> > This bug may be responsible for a warning I got running
> >
> >     while :; do yavta -c3 /dev/video0; done
> >
> > on an xHCI controller which failed under this workload.
> > I had no luck reproducing this warning again to confirm.
> >
> > xhci_hcd 0000:09:00.0: HC died; cleaning up
> > usb 13-2: USB disconnect, device number 2
> > WARNING: CPU: 2 PID: 29386 at drivers/media/common/videobuf2/videobuf2-core.c:1803 vb2_start_streaming+0xac/0x120
> >
> > Fixes: 7dd56c47784a ("media: uvcvideo: Remove stream->is_streaming field")
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Michal Pecio <michal.pecio@...il.com>
> Reviewed-by: Ricardo Ribalda <ribalda@...omium.org>
> 
> > ---
> >  drivers/media/usb/uvc/uvc_queue.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > index 790184c9843d..f49c538618bc 100644
> > --- a/drivers/media/usb/uvc/uvc_queue.c
> > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > @@ -177,7 +177,7 @@ static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
> >
> >         ret = uvc_pm_get(stream->dev);
> >         if (ret)
> > -               return ret;
> > +               goto return_buffers;
> >
> >         queue->buf_used = 0;
> >
> > @@ -187,6 +187,7 @@ static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
> >
> >         uvc_pm_put(stream->dev);
> >
> > +return_buffers:
> >         uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
> >
> >         return ret;

Error labels should start with err_. I'd like to take this as an
opportunity to reorganize the error path with something like

	ret = uvc_pm_get(stream->dev);
	if (ret)
		goto err_buffers;
 
	queue->buf_used = 0;

	ret = uvc_video_start_streaming(stream);
	if (ret)
		goto err_pm;

	return 0;
 
err_pm:
	uvc_pm_put(stream->dev);
err_buffers:
	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
	return ret;


I'll send a v2 that does this.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

-- 
Regards,

Laurent Pinchart