[PATCH] drm/fb-helper: Fix potential NULL pointer dereference

[Daniel Vetter]

On Tue, Dec 05, 2017 at 11:46:28AM -0600, Gustavo A. R. Silva wrote:
> fb_helper is being dereferenced before it is null checked,
> hence there is a potential null pointer dereference.
> 
> Fix this by moving the pointer dereference after fb_helper
> has been null checked.
> 
> This issue was detected with the help of Coccinelle.
> 
> Fixes: c777990fb45b ("drm/fb-helper: Handle function NULL argument")
> Signed-off-by: Gustavo A. R. Silva <garsilva at embeddedor.com>

Oops. Applied to drm-misc-next, thanks for your patch.
-Daniel

> ---
>  drivers/gpu/drm/drm_fb_helper.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 6654f2f..04a3a5c 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -178,7 +178,7 @@ EXPORT_SYMBOL(drm_fb_helper_add_one_connector);
>   */
>  int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
>  {
> -	struct drm_device *dev = fb_helper->dev;
> +	struct drm_device *dev;
>  	struct drm_connector *connector;
>  	struct drm_connector_list_iter conn_iter;
>  	int i, ret = 0;
> @@ -186,6 +186,8 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
>  	if (!drm_fbdev_emulation || !fb_helper)
>  		return 0;
>  
> +	dev = fb_helper->dev;
> +
>  	mutex_lock(&fb_helper->lock);
>  	drm_connector_list_iter_begin(dev, &conn_iter);
>  	drm_for_each_connector_iter(connector, &conn_iter) {
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch