linux-kernel - Re: [PATCH] drm/gma500: fix memory disclosures due to uninitialized bytes

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Date:   Tue, 22 Oct 2019 10:59:27 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Kangjie Lu <kjlu@....edu>
Cc:     Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/gma500: fix memory disclosures due to uninitialized
 bytes

On Thu, Oct 17, 2019 at 11:41:50PM -0500, Kangjie Lu wrote:
> "clock" may be copied to "best_clock". Initializing best_clock
> is not sufficient. The fix initializes clock as well to avoid
> memory disclosures and informaiton leaks.
> 
> Signed-off-by: Kangjie Lu <kjlu@....edu>

Again no leak here, but also doesn't hurt, so applied.
-Daniel

> ---
>  drivers/gpu/drm/gma500/oaktrail_crtc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/gma500/oaktrail_crtc.c b/drivers/gpu/drm/gma500/oaktrail_crtc.c
> index 167c10767dd4..900e5499249d 100644
> --- a/drivers/gpu/drm/gma500/oaktrail_crtc.c
> +++ b/drivers/gpu/drm/gma500/oaktrail_crtc.c
> @@ -129,6 +129,7 @@ static bool mrst_sdvo_find_best_pll(const struct gma_limit_t *limit,
>  	s32 freq_error, min_error = 100000;
>  
>  	memset(best_clock, 0, sizeof(*best_clock));
> +	memset(&clock, 0, sizeof(clock));
>  
>  	for (clock.m = limit->m.min; clock.m <= limit->m.max; clock.m++) {
>  		for (clock.n = limit->n.min; clock.n <= limit->n.max;
> @@ -185,6 +186,7 @@ static bool mrst_lvds_find_best_pll(const struct gma_limit_t *limit,
>  	int err = target;
>  
>  	memset(best_clock, 0, sizeof(*best_clock));
> +	memset(&clock, 0, sizeof(clock));
>  
>  	for (clock.m = limit->m.min; clock.m <= limit->m.max; clock.m++) {
>  		for (clock.p1 = limit->p1.min; clock.p1 <= limit->p1.max;
> -- 
> 2.17.1
> 

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