[PATCH] drm/vmwgfx: fix integer overflow in vmw_surface_define_ioctl()

[Thomas Hellstrom]

Hi,

On 03/28/2017 05:10 AM, Li Qiang wrote:
> In vmw_surface_define_ioctl(), the 'num_sizes' is the sum of the
> 'req->mip_levels' array. This array can be assigned any value from
> the user space. As both the 'num_sizes' and the array is uint32_t,
> it is easy to make 'num_sizes' overflow. The later 'mip_levels' is
> used as the loop count. This can lead an oob write. Add the check of
> 'req->mip_levels' to avoid this.
>
> Signed-off-by: Li Qiang <liqiang6-s at 360.cn>
> ---

Thanks. Reviewed and queued for vmwgfx-fixes.

/Thomas


>  drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> index b445ce9..ef8bf83 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> @@ -713,8 +713,11 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
>  			128;
>  
>  	num_sizes = 0;
> -	for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i)
> +	for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i) {
> +		if (req->mip_levels[i] > DRM_VMW_MAX_MIP_LEVELS)
> +			return -EINVAL;
>  		num_sizes += req->mip_levels[i];
> +	}
>  
>  	if (num_sizes > DRM_VMW_MAX_SURFACE_FACES *
>  	    DRM_VMW_MAX_MIP_LEVELS)