ACK: [CVE-2017-7261][PATCH T] drm/vmwgfx: NULL pointer dereference in vmw_surface_define_ioctl()

[Stefan Bader]

On 19.07.2017 09:45, Po-Hsu Lin wrote:
> From: Murray McAllister <murray.mcallister at insomniasec.com>
> 
> CVE-2017-7261
> 
> Before memory allocations vmw_surface_define_ioctl() checks the
> upper-bounds of a user-supplied size, but does not check if the
> supplied size is 0.
> 
> Add check to avoid NULL pointer dereferences.
> 
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Murray McAllister <murray.mcallister at insomniasec.com>
> Reviewed-by: Sinclair Yeh <syeh at vmware.com>
> (cherry picked from commit 36274ab8c596f1240c606bb514da329add2a1bcd)
> Signed-off-by: Po-Hsu Lin <po-hsu.lin at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>

> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> index 9593df6..196833b 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> @@ -711,8 +711,8 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
>  		num_sizes += req->mip_levels[i];
>  	}
>  
> -	if (num_sizes > DRM_VMW_MAX_SURFACE_FACES *
> -	    DRM_VMW_MAX_MIP_LEVELS)
> +	if (num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS ||
> +	    num_sizes == 0)
>  		return -EINVAL;
>  
>  	size = vmw_user_surface_size + 128 +
> 


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