linux-kernel - Re: [PATCH V3] drm_crtc: check if fb_create return NULL

Open Source and information security mailing list archives

Date:	Thu, 24 Jan 2013 10:31:48 +0200
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	"Su\, Xuemin" <xuemin.su@...el.com>, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:	xuemin.su@...el.com, yanmin_zhang@...ux.intel.com, bo.he@...el.com
Subject: Re: [PATCH V3] drm_crtc: check if fb_create return NULL

On Thu, 24 Jan 2013, "Su, Xuemin" <xuemin.su@...el.com> wrote:
> From: xueminsu <xuemin.su@...el.com>
> Date: Tue, 22 Jan 2013 22:39:39 +0800
> Subject: [PATCH] drm_crtc: check if fb_create return NULL
>
> Some buggy driver may still return NULL in fb_create,
> which leads to kernel panic.
>
> Signed-off-by: xueminsu <xuemin.su@...el.com>
> ---
>  drivers/gpu/drm/drm_crtc.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index f2d667b..ae613ec 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -2172,6 +2172,8 @@ int drm_mode_addfb(struct drm_device *dev,
>  		ret = PTR_ERR(fb);
>  		goto out;
>  	}
> +	/* some buggy driver may return NULL here, which may cause panic */
> +	BUG_ON(!fb);

I fail to see the benefit of this compared to just letting it oops...

>  	or->fb_id = fb->base.id;

...right here.

BR,
Jani.

>  	list_add(&fb->filp_head, &file_priv->fbs);
> -- 
> 1.7.6
>
>
>
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