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Date:   Fri, 16 Jul 2021 09:54:49 +0200
From:   Johan Hovold <johan@kernel.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        syzbot+faf11bbadc5a372564da@syzkaller.appspotmail.com,
        Antti Palosaari <crope@iki.fi>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Subject: Re: [PATCH 5.13 252/266] media: rtl28xxu: fix zero-length control
 request
Message-ID: <YPE7Se31LQnaikuy@hovoldconsulting.com>
References: <20210715182613.933608881@linuxfoundation.org>
 <20210715182652.248759867@linuxfoundation.org>
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On Thu, Jul 15, 2021 at 08:40:07PM +0200, Greg Kroah-Hartman wrote:
> From: Johan Hovold <johan@kernel.org>
> 
> commit 25d5ce3a606a1eb23a9265d615a92a876ff9cb5f upstream.
> 
> 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>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Please drop this patch from all stable trees. 

This patch causes a regression and a second version was sent almost two
months ago, but I'm not getting any response whatsoever from the media
maintainers. 

I resent the correct fix and a revert of this one almost a month ago and
the cover letter includes some further details:

	https://lore.kernel.org/r/20210623084521.7105-1-johan@kernel.org

But this still hasn't been fixed in linux-next.

> ---
>  drivers/media/usb/dvb-usb-v2/rtl28xxu.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> --- 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 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");
>  
> 
> 

Johan