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From:   Kieran Bingham <kieran.bingham@ideasonboard.com>
To:     linux-media@vger.kernel.org,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Edgar Thier <info@edgarthier.net>
Cc:     Kieran Bingham <kieran.bingham@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] media: uvcvideo: Prevent setting unavailable flags
Date:   Wed, 21 Mar 2018 15:43:08 +0000
Message-Id: <1521646988-803-1-git-send-email-kieran.bingham@ideasonboard.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The addition of an extra operation to use the GET_INFO command
overwrites all existing flags from the uvc_ctrls table. This includes
setting all controls as supporting  GET_MIN, GET_MAX, GET_RES, and
GET_DEF regardless of whether they do or not.

Move the initialisation of these control capabilities directly to the
uvc_ctrl_fill_xu_info() call where they were originally located in that
use case, and ensure that the new functionality in uvc_ctrl_get_flags()
will only set flags based on their reported capability from the GET_INFO
call.

Fixes: 859086ae3636 ("media: uvcvideo: Apply flags from device to actual
properties")

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 1daf444371be..4042cbdb721b 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1607,14 +1607,12 @@ static int uvc_ctrl_get_flags(struct uvc_device *dev,
 	ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id, dev->intfnum,
 			     info->selector, data, 1);
 	if (!ret)
-		info->flags = UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX
-			    | UVC_CTRL_FLAG_GET_RES | UVC_CTRL_FLAG_GET_DEF
-			    | (data[0] & UVC_CONTROL_CAP_GET ?
-			       UVC_CTRL_FLAG_GET_CUR : 0)
-			    | (data[0] & UVC_CONTROL_CAP_SET ?
-			       UVC_CTRL_FLAG_SET_CUR : 0)
-			    | (data[0] & UVC_CONTROL_CAP_AUTOUPDATE ?
-			       UVC_CTRL_FLAG_AUTO_UPDATE : 0);
+		info->flags |= (data[0] & UVC_CONTROL_CAP_GET ?
+				UVC_CTRL_FLAG_GET_CUR : 0)
+			    |  (data[0] & UVC_CONTROL_CAP_SET ?
+				UVC_CTRL_FLAG_SET_CUR : 0)
+			    |  (data[0] & UVC_CONTROL_CAP_AUTOUPDATE ?
+				UVC_CTRL_FLAG_AUTO_UPDATE : 0);
 
 	kfree(data);
 	return ret;
@@ -1689,6 +1687,9 @@ static int uvc_ctrl_fill_xu_info(struct uvc_device *dev,
 
 	info->size = le16_to_cpup((__le16 *)data);
 
+	info->flags = UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX
+		    | UVC_CTRL_FLAG_GET_RES | UVC_CTRL_FLAG_GET_DEF;
+
 	ret = uvc_ctrl_get_flags(dev, ctrl, info);
 	if (ret < 0) {
 		uvc_trace(UVC_TRACE_CONTROL,
-- 
2.7.4