[PATCH 4.14 101/178] media: usbtv: fix brightness and contrast controls

From: Greg Kroah-Hartman
Date: Mon Dec 18 2017 - 11:38:34 EST

4.14-stable review patch. If anyone has any objections, please let me know.


From: Adam Sampson <ats@xxxxxxxxx>

[ Upstream commit b3168c87c0492661badc3e908f977d79e7738a41 ]

Because the brightness and contrast controls share a register,
usbtv_s_ctrl needs to read the existing values for both controls before
inserting the new value. However, the code accidentally wrote to the
registers (from an uninitialised stack array), rather than reading them.

The user-visible effect of this was that adjusting the brightness would
also set the contrast to a random value, and vice versa -- so it wasn't
possible to correctly adjust the brightness of usbtv's video output.

Tested with an "EasyDAY" UTV007 device.

Fixes: c53a846c48f2 ("usbtv: add video controls")

Signed-off-by: Adam Sampson <ats@xxxxxxxxx>
Reviewed-by: Lubomir Rintel <lkundrak@xxxxx>
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/media/usb/usbtv/usbtv-video.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/media/usb/usbtv/usbtv-video.c
+++ b/drivers/media/usb/usbtv/usbtv-video.c
@@ -718,8 +718,8 @@ static int usbtv_s_ctrl(struct v4l2_ctrl
if (ctrl->id == V4L2_CID_BRIGHTNESS || ctrl->id == V4L2_CID_CONTRAST) {
ret = usb_control_msg(usbtv->udev,
- usb_sndctrlpipe(usbtv->udev, 0), USBTV_CONTROL_REG,
+ usb_rcvctrlpipe(usbtv->udev, 0), USBTV_CONTROL_REG,
0, USBTV_BASE + 0x0244, (void *)data, 3, 0);
if (ret < 0)
goto error;