Re: [PATCH v2 i-g-t 1/4] igt_kms: Avoid NULL ptr deref when commiting disabled planes

Konduru, Chandra
2015-05-06T20:47:24Z

> -----Original Message-----
> From: Tvrtko Ursulin [mailto:tvrtko.ursulin@linux.intel.com]
> Sent: Tuesday, May 05, 2015 2:53 AM
> To: Intel-gfx@lists.freedesktop.org
> Cc: Ursulin, Tvrtko; Konduru, Chandra; Wood, Thomas
> Subject: [PATCH v2 i-g-t 1/4] igt_kms: Avoid NULL ptr deref when commiting
> disabled planes
>
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> I think;
>
> commit a26f9f9ad0e679c7ce413a25d34f6914e1174151
> Author: chandra konduru <chandra.konduru@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.
>
> v2: Split out igt_plane_set_fb cleanup. (Thomas Wood)
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: chandra konduru <chandra.konduru@intel.com>
> Cc: Thomas Wood <thomas.wood@intel.com>
> ---
> There might be a better fix, but this works for me.
> ---
> lib/igt_kms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c index b7d1e90..33d437d 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) {

Shouldn't this include plane->position_changed too? Like:
if ((plane->fb_changed || plane->size_changed || plane->position_changed) && fb_id == 0) {

> LOG(display,
> "%s: SetPlane pipe %s, plane %d, disabling\n",
> igt_output_name(output),
> --
> 2.3.5