V4L/DVB: uvcvideo: Clamp control values to the minimum and maximum values

When setting a control, the V4L2 specification requires drivers to
either clamp the control value to the [minimum, maximum] range or return
the -ERANGE error.

Fix the driver to clamp control values to the valid range in
uvc_ctrl_set() and make sure the value differs from the minimum by an
integer multiple of step.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 45 insertions, 4 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 5ff501390842..f38bc6bbc3d2 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1021,19 +1021,57 @@ int uvc_ctrl_set(struct uvc_video_chain *chain,
 {
         struct uvc_control *ctrl;
         struct uvc_control_mapping *mapping;
-        s32 value = xctrl->value;
+        s32 value;
+        u32 step;
+        s32 min;
+        s32 max;
         int ret;
 
         ctrl = uvc_find_control(chain, xctrl->id, &mapping);
         if (ctrl == NULL || (ctrl->info->flags & UVC_CONTROL_SET_CUR) == 0)
                 return -EINVAL;
 
-        if (mapping->v4l2_type == V4L2_CTRL_TYPE_MENU) {
-                if (value < 0 || value >= mapping->menu_count)
+        /* Clamp out of range values. */
+        switch (mapping->v4l2_type) {
+        case V4L2_CTRL_TYPE_INTEGER:
+                if (!ctrl->cached) {
+                        ret = uvc_ctrl_populate_cache(chain, ctrl);
+                        if (ret < 0)
+                                return ret;
+                }
+
+                min = mapping->get(mapping, UVC_GET_MIN,
+                                   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
+                max = mapping->get(mapping, UVC_GET_MAX,
+                                   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
+                step = mapping->get(mapping, UVC_GET_RES,
+                                    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
+
+                xctrl->value = min + (xctrl->value - min + step/2) / step * step;
+                xctrl->value = clamp(xctrl->value, min, max);
+                value = xctrl->value;
+                break;
+
+        case V4L2_CTRL_TYPE_BOOLEAN:
+                xctrl->value = clamp(xctrl->value, 0, 1);
+                value = xctrl->value;
+                break;
+
+        case V4L2_CTRL_TYPE_MENU:
+                if (xctrl->value < 0 || xctrl->value >= mapping->menu_count)
                         return -ERANGE;
-                value = mapping->menu_info[value].value;
+                value = mapping->menu_info[xctrl->value].value;
+                break;
+
+        default:
+                value = xctrl->value;
+                break;
         }
 
+        /* If the mapping doesn't span the whole UVC control, the current value
+         * needs to be loaded from the device to perform the read-modify-write
+         * operation.
+         */
         if (!ctrl->loaded && (ctrl->info->size * 8) != mapping->size) {
                 if ((ctrl->info->flags & UVC_CONTROL_GET_CUR) == 0) {
                         memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
@@ -1051,6 +1089,7 @@ int uvc_ctrl_set(struct uvc_video_chain *chain,
                 ctrl->loaded = 1;
         }
 
+        /* Backup the current value in case we need to rollback later. */
         if (!ctrl->dirty) {
                 memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
                        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c
index 23239a4adefe..bf1fc7f29ca7 100644
--- a/drivers/media/video/uvc/uvc_v4l2.c
+++ b/drivers/media/video/uvc/uvc_v4l2.c
@@ -549,6 +549,8 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
                         return ret;
                 }
                 ret = uvc_ctrl_commit(chain);
+                if (ret == 0)
+                        ctrl->value = xctrl.value;
                 break;
         }