Re: [PATCH 3/3] media: rtl28xxu: fix zero-length control request

From: Johan Hovold <johan@kernel.org>
To: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
	linux-media@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	syzbot+faf11bbadc5a372564da@syzkaller.appspotmail.com,
	stable@vger.kernel.org, Antti Palosaari <crope@iki.fi>
Subject: Re: [PATCH 3/3] media: rtl28xxu: fix zero-length control request
Date: Mon, 7 Jun 2021 09:34:32 +0200	[thread overview]
Message-ID: <YL3MCGY5wTsW2kEF@hovoldconsulting.com> (raw)
In-Reply-To: <YLSWeyy1skooTmqD@hovoldconsulting.com>

On Mon, May 31, 2021 at 09:55:39AM +0200, Johan Hovold wrote:
> On Mon, May 24, 2021 at 01:09:20PM +0200, Johan Hovold wrote:
> > The direction of the pipe argument must match the request-type direction
> > bit or control requests may fail depending on the host-controller-driver
> > implementation.
> > 
> > Control transfers without a data stage are treated as OUT requests by
> > the USB stack and should be using usb_sndctrlpipe(). Failing to do so
> > will now trigger a warning.
> > 
> > Fix the zero-length i2c-read request used for type detection by
> > attempting to read a single byte instead.
> > 
> > Reported-by: syzbot+faf11bbadc5a372564da@syzkaller.appspotmail.com
> > Fixes: d0f232e823af ("[media] rtl28xxu: add heuristic to detect chip type")
> > Cc: stable@vger.kernel.org      # 4.0
> > Cc: Antti Palosaari <crope@iki.fi>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > ---
> >  drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
> > index 97ed17a141bb..2c04ed8af0e4 100644
> > --- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
> > +++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
> > @@ -612,8 +612,9 @@ static int rtl28xxu_read_config(struct dvb_usb_device *d)
> >  static int rtl28xxu_identify_state(struct dvb_usb_device *d, const char **name)
> >  {
> >  	struct rtl28xxu_dev *dev = d_to_priv(d);
> > +	u8 buf[1];
> >  	int ret;
> > -	struct rtl28xxu_req req_demod_i2c = {0x0020, CMD_I2C_DA_RD, 0, NULL};
> > +	struct rtl28xxu_req req_demod_i2c = {0x0020, CMD_I2C_DA_RD, 1, buf};
> >  
> >  	dev_dbg(&d->intf->dev, "\n");
> 
> As reported here
> 
> 	https://lore.kernel.org/r/YLSVsrhMZ2oOL1vM@hovoldconsulting.com
> 
> this patch is causing the chip type to no longer be detected correctly,
> so please drop this one for now until this has been resolved.

Looks like this one was applied to the media tree a couple of days after
I sent this nonetheless.

Can you drop this one in favour of the v2 posted here:

	 https://lore.kernel.org/r/20210531094434.12651-4-johan@kernel.org

or do you want me to send an incremental fix instead?

Johan