Re: [PATCH v6 2/2] drm: Prevent release fb after cleanup mode config
From: Sean Paul
Date: Mon Apr 10 2017 - 16:31:34 EST
On Mon, Apr 10, 2017 at 06:00:45PM +0800, Jeffy Chen wrote:
> After unbinding drm, the user space may still owns the drm dev fd,
> and may trigger fb release after cleanup mode config.
>
> Add a sanity check to prevent that.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
> ---
>
> Changes in v6: None
> Changes in v5: None
> Changes in v2: None
>
> drivers/gpu/drm/drm_framebuffer.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
> index e8f9c13..03c1632 100644
> --- a/drivers/gpu/drm/drm_framebuffer.c
> +++ b/drivers/gpu/drm/drm_framebuffer.c
> @@ -583,6 +583,11 @@ void drm_fb_release(struct drm_file *priv)
> {
> struct drm_framebuffer *fb, *tfb;
> struct drm_mode_rmfb_work arg;
> + struct drm_minor *minor = priv->minor;
> + struct drm_device *dev = minor->dev;
> +
> + if (WARN_ON(!dev->mode_config.num_fb && !list_empty(&priv->fbs)))
Have you actually seen this happen? num_fb should be tightly couple to
priv->fbs, so it seems like this could only result from a driver bug (or I'm not
reading the code correctly).
Sean
> + return;
>
> INIT_LIST_HEAD(&arg.fbs);
>
> --
> 2.1.4
>
--
Sean Paul, Software Engineer, Google / Chromium OS