linux-kernel - Re: [PATCH] efifb: Don't show the mapping VA

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Message-ID: <20160512201910.GD1973@redhat.com>
Date:	Thu, 12 May 2016 16:19:10 -0400
From:	Peter Jones <pjones@...hat.com>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Matt Fleming <matt@...eblueprint.co.uk>
Subject: Re: [PATCH] efifb: Don't show the mapping VA

On Wed, May 11, 2016 at 04:57:47PM -0700, Andy Lutomirski wrote:
> The framebuffer mapping virtual address leaks information about the
> kernel memory layout.  Stop logging it.
> 
> Cc: Peter Jones <pjones@...hat.com>
> Cc: Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: linux-fbdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Andy Lutomirski <luto@...nel.org>

In practice it also hasn't ever helped any actual debugging.

Signed-off-by: Peter Jones <pjones@...hat.com>

> ---
>  drivers/video/fbdev/efifb.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
> index 95d293b7445a..3dcaf4e82885 100644
> --- a/drivers/video/fbdev/efifb.c
> +++ b/drivers/video/fbdev/efifb.c
> @@ -247,10 +247,8 @@ static int efifb_probe(struct platform_device *dev)
>  		goto err_release_fb;
>  	}
>  
> -	printk(KERN_INFO "efifb: framebuffer at 0x%lx, mapped to 0x%p, "
> -	       "using %dk, total %dk\n",
> -	       efifb_fix.smem_start, info->screen_base,
> -	       size_remap/1024, size_total/1024);
> +	printk(KERN_INFO "efifb: framebuffer at 0x%lx, using %dk, total %dk\n",
> +	       efifb_fix.smem_start, size_remap/1024, size_total/1024);
>  	printk(KERN_INFO "efifb: mode is %dx%dx%d, linelength=%d, pages=%d\n",
>  	       efifb_defined.xres, efifb_defined.yres,
>  	       efifb_defined.bits_per_pixel, efifb_fix.line_length,
> -- 
> 2.5.5
> 
> --
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-- 
  Peter