V4L/DVB (5869): Add check for valid control ID to v4l2_ctrl_next.

If v4l2_ctrl_next is called without the V4L2_CTRL_FLAG_NEXT_CTRL then it 
should check whether the passed control ID is valid and return 0 if it 
isn't. Otherwise a for-loop over the control IDs will never end.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index 13ee550d3215..d2915d3530ea 100644
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -939,16 +939,25 @@ int v4l2_ctrl_query_menu(struct v4l2_querymenu *qmenu, struct v4l2_queryctrl *qc
    When no more controls are available 0 is returned. */
 u32 v4l2_ctrl_next(const u32 * const * ctrl_classes, u32 id)
 {
-        u32 ctrl_class;
+        u32 ctrl_class = V4L2_CTRL_ID2CLASS(id);
         const u32 *pctrl;
 
-        /* if no query is desired, then just return the control ID */
-        if ((id & V4L2_CTRL_FLAG_NEXT_CTRL) == 0)
-                return id;
         if (ctrl_classes == NULL)
                 return 0;
+
+        /* if no query is desired, then check if the ID is part of ctrl_classes */
+        if ((id & V4L2_CTRL_FLAG_NEXT_CTRL) == 0) {
+                /* find class */
+                while (*ctrl_classes && V4L2_CTRL_ID2CLASS(**ctrl_classes) != ctrl_class)
+                        ctrl_classes++;
+                if (*ctrl_classes == NULL)
+                        return 0;
+                pctrl = *ctrl_classes;
+                /* find control ID */
+                while (*pctrl && *pctrl != id) pctrl++;
+                return *pctrl ? id : 0;
+        }
         id &= V4L2_CTRL_ID_MASK;
-        ctrl_class = V4L2_CTRL_ID2CLASS(id);
         id++;   /* select next control */
         /* find first class that matches (or is greater than) the class of
            the ID */