[Intel-gfx] [PATCH i-g-t] igt_kms: Avoid NULL ptr deref when commiting disabled planes

[Thomas Wood]

On 28 April 2015 at 11:57, Tvrtko Ursulin
<tvrtko.ursulin at linux.intel.com> wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>
> I think;
>
>    commit a26f9f9ad0e679c7ce413a25d34f6914e1174151
>    Author: chandra konduru <chandra.konduru at intel.com>
>    Date:   Mon Mar 30 13:52:04 2015 -0700
>
>        i-g-t: Adding plane scaling test case
>
> introduced a condition where it attempts to update a disabled plane because
> of the newly introduced size_changed flag which is set for disabled frame
> buffers. Result is a NULL ptr deref in igt_drm_plane_commit (plane->fb->src_x).
>
> Start recognising this case as disabled plane and act accordingly.
>
> Also cleanup the code in igt_plane_set_fb a bit.

The changes to igt_plane_set_fb look fine, but should really go in a
separate patch.


>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: chandra konduru <chandra.konduru at intel.com>
> ---
> There might be a better fix, but this works for me.
> ---
>  lib/igt_kms.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index b7d1e90..b5ba273 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -1331,7 +1331,7 @@ static int igt_drm_plane_commit(igt_plane_t *plane,
>         fb_id = igt_plane_get_fb_id(plane);
>         crtc_id = output->config.crtc->crtc_id;
>
> -       if (plane->fb_changed && fb_id == 0) {
> +       if ((plane->fb_changed || plane->size_changed) && fb_id == 0) {
>                 LOG(display,
>                     "%s: SetPlane pipe %s, plane %d, disabling\n",
>                     igt_output_name(output),
> @@ -1765,14 +1765,6 @@ void igt_plane_set_fb(igt_plane_t *plane, struct igt_fb *fb)
>         plane->fb = fb;
>         /* hack to keep tests working that don't call igt_plane_set_size() */
>         if (fb) {
> -               plane->crtc_w = fb->width;
> -               plane->crtc_h = fb->height;
> -       } else {
> -               plane->crtc_w = 0;
> -               plane->crtc_h = 0;
> -       }
> -
> -       if (fb) {
>                 /* set default plane pos/size as fb size */
>                 plane->crtc_x = 0;
>                 plane->crtc_y = 0;
> @@ -1784,6 +1776,9 @@ void igt_plane_set_fb(igt_plane_t *plane, struct igt_fb *fb)
>                 fb->src_y = 0;
>                 fb->src_w = fb->width;
>                 fb->src_h = fb->height;
> +       } else {
> +               plane->crtc_w = 0;
> +               plane->crtc_h = 0;
>         }
>
>         plane->fb_changed = true;
> --
> 2.3.5
>
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