media: uvcvideo: Avoid invalid memory access

If mappings points to an invalid memory, we will be invalid accessing
it. Solve it by initializing the value of the variable mapping and by
changing the order in the conditional statement (to avoid accessing
mapping->id if not needed).

Fix:
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN NOPTI

Fixes: 6350d6a4ed487 ("media: uvcvideo: Set error_idx during ctrl_commit errors")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 30bfe9069a1fb4e5cc392acf41e9de3f1c996929..9a25d60292558a4a48b3a770399d7359620cf205 100644 (file)
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1638,7 +1638,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
                                  struct v4l2_ext_controls *ctrls,
                                  struct uvc_control *uvc_control)
 {
-       struct uvc_control_mapping *mapping;
+       struct uvc_control_mapping *mapping = NULL;
        struct uvc_control *ctrl_found;
        unsigned int i;