Re: [PATCH 1/1] drm: avoid exposing kernel stack in compat_drm_getstats

[Daniel Vetter]

On Sun, Aug 21, 2016 at 07:56:19PM +0200, Heinrich Schuchardt wrote:
> The C standard does not specify the size of the integer used
> to store an enum. Hence in structure drm_stats32_t alignment
> bytes may exist.
> 
> To avoid exposing bytes from the kernel stack it is
> necessary to initialize variable s32 completely.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@xxxxxx>

Applied to drm-misc, thanks.
-Daniel

> ---
>  drivers/gpu/drm/drm_ioc32.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
> index 57676f8..32a489b 100644
> --- a/drivers/gpu/drm/drm_ioc32.c
> +++ b/drivers/gpu/drm/drm_ioc32.c
> @@ -346,6 +346,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
>  	struct drm_stats __user *stats;
>  	int i, err;
>  
> +	memset(&s32, 0, sizeof(drm_stats32_t));
>  	stats = compat_alloc_user_space(sizeof(*stats));
>  	if (!stats)
>  		return -EFAULT;
> -- 
> 2.1.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch