re: media: staging/imx: Improve pipeline searching (bug report)

[Colin Ian King <colin.king@canonical.com>]

Hi,

Static analysis with Coverity on Linux next has found a potential issue
with the following commit:

commit 3ef46bc97ca2c918b7657a08220c7340a9bb07a2
Author: Steve Longerbeam <slongerbeam@gmail.com>
Date:   Fri May 10 17:50:11 2019 -0400

    media: staging/imx: Improve pipeline searching


The issue is in drivers/staging/media/imx/imx-media-utils.c in function
find_pipeline_entity:

        struct media_pad *pad = NULL;

pad is assigned a NULL

        struct video_device *vfd;
        struct v4l2_subdev *sd;

        if (grp_id && is_media_entity_v4l2_subdev(start)) {
                sd = media_entity_to_v4l2_subdev(start);
                if (sd->grp_id & grp_id)
                        return &sd->entity;
        } else if (buftype && is_media_entity_v4l2_video_device(start)) {
                vfd = media_entity_to_video_device(pad->entity);

..and above the null pad is being dereferenced causing a kernel oops.

                if (buftype == vfd->queue->type)
                        return &vfd->entity;
        }


Colin