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

From: "Konduru, Chandra" <chandra.konduru@intel.com>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	"Intel-gfx@lists.freedesktop.org"
	<Intel-gfx@lists.freedesktop.org>
Cc: "Wood, Thomas" <thomas.wood@intel.com>
Subject: Re: [PATCH v2 i-g-t 1/4] igt_kms: Avoid NULL ptr deref when commiting disabled planes
Date: Wed, 6 May 2015 20:47:20 +0000	[thread overview]
Message-ID: <76A9B330A4D78C4D99CB292C4CC06C0E36FC745A@fmsmsx101.amr.corp.intel.com> (raw)
In-Reply-To: <1430819603-492-1-git-send-email-tvrtko.ursulin@linux.intel.com>


> -----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

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