From: "Daniel W. S. Almeida" <dwlsalme...@gmail.com>

Fixes the following coccinelle report:

drivers/media/usb/uvc/uvc_ctrl.c:1860:5-11:
ERROR: invalid reference to the index variable of the iterator on line 1854

By introducing a temporary variable to iterate the list.

Do not dereference the 'entity' pointer if it is not found in the list.

Found using - Coccinelle (http://coccinelle.lip6.fr)

Signed-off-by: Daniel W. S. Almeida <dwlsalme...@gmail.com>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index e399b9fad757..567bdedc2ff2 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1842,7 +1842,8 @@ static int uvc_ctrl_init_xu_ctrl(struct uvc_device *dev,
 int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
        struct uvc_xu_control_query *xqry)
 {
-       struct uvc_entity *entity;
+       struct uvc_entity *entity = NULL;
+       struct uvc_entity *cursor = NULL;
        struct uvc_control *ctrl;
        unsigned int i, found = 0;
        u32 reqflags;
@@ -1851,13 +1852,15 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
        int ret;
 
        /* Find the extension unit. */
-       list_for_each_entry(entity, &chain->entities, chain) {
-               if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT &&
-                   entity->id == xqry->unit)
+       list_for_each_entry(cursor, &chain->entities, chain) {
+               if (UVC_ENTITY_TYPE(cursor) == UVC_VC_EXTENSION_UNIT &&
+                   cursor->id == xqry->unit) {
+                       entity = cursor;
                        break;
+                   }
        }
 
-       if (entity->id != xqry->unit) {
+       if (!entity || entity->id != xqry->unit) {
                uvc_trace(UVC_TRACE_CONTROL, "Extension unit %u not found.\n",
                        xqry->unit);
                return -ENOENT;
-- 
2.28.0

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