linux-kernel - Re: [PATCH] drm/gma500: dont expose bytes from kernel stack

Open Source and information security mailing list archives

Date:   Mon, 22 Aug 2016 09:29:17 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Heinrich Schuchardt <xypron.glpk@....de>
Cc:     Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/gma500: dont expose bytes from kernel stack

On Sun, Aug 21, 2016 at 08:39:38PM +0200, Heinrich Schuchardt wrote:
> Components m1, m2, p2, dot, vco of variable clock should be
> initialized to avoid bytes from the kernel stack to be
> exposed.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>

Might be a silly question, but where exactly would we expose these bytes?
This isn't directly called by an ioctl, I have no idea how those bytes
might get to userspace ...
-Daniel
> ---
>  drivers/gpu/drm/gma500/oaktrail_crtc.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/gma500/oaktrail_crtc.c b/drivers/gpu/drm/gma500/oaktrail_crtc.c
> index da9fd34..28bd8f3 100644
> --- a/drivers/gpu/drm/gma500/oaktrail_crtc.c
> +++ b/drivers/gpu/drm/gma500/oaktrail_crtc.c
> @@ -138,6 +138,7 @@ static bool mrst_sdvo_find_best_pll(const struct gma_limit_t *limit,
>  	u32 target_vco, actual_freq;
>  	s32 freq_error, min_error = 100000;
>  
> +	memset(clock, 0, sizeof(struct gma_clock_t));
>  	memset(best_clock, 0, sizeof(*best_clock));
>  
>  	for (clock.m = limit->m.min; clock.m <= limit->m.max; clock.m++) {
> -- 
> 2.1.4
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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