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media: gspca/gl860: fix zero-length control requests

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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 gl860_RTx() helper so that zero-length control reads fail with
an error message instead. Note that there are no current callers that
would trigger this.

Fixes: 4f7cb8837c ("V4L/DVB (12954): gspca - gl860: Addition of GL860 based webcams")
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>
This commit is contained in:
Johan Hovold 2021-05-24 13:09:18 +02:00 committed by Mauro Carvalho Chehab
parent 5eabfbdd7d
commit 8ed339f23d
1 changed files with 2 additions and 2 deletions
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4
drivers/media/usb/gspca/gl860/gl860.c
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@ -561,8 +561,8 @@ int gl860_RTx(struct gspca_dev *gspca_dev,
len, 400 + 200 * (len > 1));
memcpy(pdata, gspca_dev->usb_buf, len);
} else {
r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
req, pref, val, index, NULL, len, 400);
gspca_err(gspca_dev, "zero-length read request\n");
r = -EINVAL;
}
}