Re: [PATCH] drm/self_refresh: Fix possible NULL deref in failure path

From: Daniel Vetter <daniel@ffwll.ch>
To: Sean Paul <sean@poorly.run>
Cc: Zain Wang <wzz@rock-chips.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Jose Souza <jose.souza@intel.com>,
	Tomasz Figa <tfiga@chromium.org>, David Airlie <airlied@linux.ie>,
	Sean Paul <seanpaul@chromium.org>,
	dri-devel@lists.freedesktop.org,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH] drm/self_refresh: Fix possible NULL deref in failure path
Date: Thu, 20 Jun 2019 13:28:55 +0200	[thread overview]
Message-ID: <20190620112855.GQ12905@phenom.ffwll.local> (raw)
In-Reply-To: <20190619181951.192305-1-sean@poorly.run>

On Wed, Jun 19, 2019 at 02:19:47PM -0400, Sean Paul wrote:
> From: Sean Paul <seanpaul@chromium.org>
> 
> If state allocation fails, we still try to give back the reference on
> it. Also initialize ret in case the crtc is not enabled and we hit the
> eject button.
> 
> Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers")
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Jose Souza <jose.souza@intel.com>
> Cc: Zain Wang <wzz@rock-chips.com>
> Cc: Tomasz Figa <tfiga@chromium.org>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Sean Paul <seanpaul@chromium.org>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Cc: Sean Paul <sean@poorly.run>
> Cc: David Airlie <airlied@linux.ie>
> Cc: dri-devel@lists.freedesktop.org
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/drm_self_refresh_helper.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c b/drivers/gpu/drm/drm_self_refresh_helper.c
> index e0d2ad1f070cb..4b9424a8f1f1c 100644
> --- a/drivers/gpu/drm/drm_self_refresh_helper.c
> +++ b/drivers/gpu/drm/drm_self_refresh_helper.c
> @@ -69,14 +69,14 @@ static void drm_self_refresh_helper_entry_work(struct work_struct *work)
>  	struct drm_connector *conn;
>  	struct drm_connector_state *conn_state;
>  	struct drm_crtc_state *crtc_state;
> -	int i, ret;
> +	int i, ret = 0;
>  
>  	drm_modeset_acquire_init(&ctx, 0);
>  
>  	state = drm_atomic_state_alloc(dev);
>  	if (!state) {
>  		ret = -ENOMEM;
> -		goto out;
> +		goto out_drop_locks;
>  	}
>  
>  retry:
> @@ -116,6 +116,8 @@ static void drm_self_refresh_helper_entry_work(struct work_struct *work)
>  	}
>  
>  	drm_atomic_state_put(state);
> +
> +out_drop_locks:
>  	drm_modeset_drop_locks(&ctx);
>  	drm_modeset_acquire_fini(&ctx);
>  }
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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