3 files changed, 44 insertions, 4 deletions

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index c95a2229f4fa..6f5aaaf09ee0 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1085,11 +1085,28 @@ static int uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
 	return 0;
 }
 
+/*
+ * Check if control @v4l2_id can be accessed by the given control @ioctl
+ * (VIDIOC_G_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS or VIDIOC_S_EXT_CTRLS).
+ *
+ * For set operations on slave controls, check if the master's value is set to
+ * manual, either in the others controls set in the same ioctl call, or from
+ * the master's current value. This catches VIDIOC_S_EXT_CTRLS calls that set
+ * both the master and slave control, such as for instance setting
+ * auto_exposure=1, exposure_time_absolute=251.
+ */
 int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
-			   bool read)
+			   const struct v4l2_ext_controls *ctrls,
+			   unsigned long ioctl)
 {
+	struct uvc_control_mapping *master_map = NULL;
+	struct uvc_control *master_ctrl = NULL;
 	struct uvc_control_mapping *mapping;
 	struct uvc_control *ctrl;
+	bool read = ioctl == VIDIOC_G_EXT_CTRLS;
+	s32 val;
+	int ret;
+	int i;
 
 	if (__uvc_query_v4l2_class(chain, v4l2_id, 0) >= 0)
 		return -EACCES;
@@ -1104,6 +1121,29 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
 	if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) && !read)
 		return -EACCES;
 
+	if (ioctl != VIDIOC_S_EXT_CTRLS || !mapping->master_id)
+		return 0;
+
+	/*
+	 * Iterate backwards in cases where the master control is accessed
+	 * multiple times in the same ioctl. We want the last value.
+	 */
+	for (i = ctrls->count - 1; i >= 0; i--) {
+		if (ctrls->controls[i].id == mapping->master_id)
+			return ctrls->controls[i].value ==
+					mapping->master_manual ? 0 : -EACCES;
+	}
+
+	__uvc_find_control(ctrl->entity, mapping->master_id, &master_map,
+			   &master_ctrl, 0);
+
+	if (!master_ctrl || !(master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
+		return 0;
+
+	ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
+	if (ret >= 0 && val != mapping->master_manual)
+		return -EACCES;
+
 	return 0;
 }
 
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index f4d4c33b6dfb..3edb54c086b2 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -1020,8 +1020,7 @@ static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
 	int ret = 0;
 
 	for (i = 0; i < ctrls->count; ++ctrl, ++i) {
-		ret = uvc_ctrl_is_accessible(chain, ctrl->id,
-					    ioctl == VIDIOC_G_EXT_CTRLS);
+		ret = uvc_ctrl_is_accessible(chain, ctrl->id, ctrls, ioctl);
 		if (ret)
 			break;
 	}
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index df93db259312..a151f583cd15 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -761,7 +761,8 @@ static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
 int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
 int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
 int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
-			   bool read);
+			   const struct v4l2_ext_controls *ctrls,
+			   unsigned long ioctl);
 
 int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
 		      struct uvc_xu_control_query *xqry);