[PATCH] drm: Clear e after kfree in drm_mode_page_flip_ioctl

[Harry Wentland]

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

On 2017-03-30 09:32 AM, Daniel Vetter wrote:
> With the explicit retry loop static analyzers get confused by the
> control flow and believe that e could be accessed after kfree. That's
> not possible, but it's non-obvious, so let's clear it to NULL.
>
> We already cleared e = NULL at the top of the function, so this is all
> in line.
>
> Cc: Julia Lawall <julia.lawall at lip6.fr>
> Reported-by: Julia Lawall <julia.lawall at lip6.fr>
> Fixes: 29dc0d1de182 ("drm: Roll out acquire context for the page_flip ioctl")
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Sean Paul <seanpaul at chromium.org>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>   drivers/gpu/drm/drm_plane.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index ec62221d64a9..3a6de27bafed 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -922,6 +922,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
>   		ret = drm_event_reserve_init(dev, file_priv, &e->base, &e->event.base);
>   		if (ret) {
>   			kfree(e);
> +			e = NULL;
>   			goto out;
>   		}
>   	}