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Subject: media: rtl28xxu: fix zero-length control request Author: Johan Hovold johan@kernel.org Date: Wed Jun 23 10:45:21 2021 +0200

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.

The driver uses a zero-length i2c-read request for type detection so update the control-request code to use usb_sndctrlpipe() in this case.

Note that actually trying to read the i2c register in question does not work as the register might not exist (e.g. depending on the demodulator) as reported by Eero Lehtinen debiangamer2@gmail.com.

Reported-by: syzbot+faf11bbadc5a372564da@syzkaller.appspotmail.com Reported-by: Eero Lehtinen debiangamer2@gmail.com Tested-by: Eero Lehtinen debiangamer2@gmail.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: Sean Young sean@mess.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org

drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

---

diff --git a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c index 0cbdb95f8d35..795a012d4020 100644 --- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c +++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c @@ -37,7 +37,16 @@ static int rtl28xxu_ctrl_msg(struct dvb_usb_device *d, struct rtl28xxu_req *req) } else { /* read */ requesttype = (USB_TYPE_VENDOR | USB_DIR_IN); - pipe = usb_rcvctrlpipe(d->udev, 0); + + /* + * Zero-length transfers must use usb_sndctrlpipe() and + * rtl28xxu_identify_state() uses a zero-length i2c read + * command to determine the chip type. + */ + if (req->size) + pipe = usb_rcvctrlpipe(d->udev, 0); + else + pipe = usb_sndctrlpipe(d->udev, 0); }

ret = usb_control_msg(d->udev, pipe, 0, requesttype, req->value,