On Tue, Aug 11, 2015 at 09:54:29AM +0200, Maarten Lankhorst wrote:
> The port is removed synchronously, but the connector delayed.
> This causes a use after free which can cause a kernel BUG with
> slug_debug=FPZU. This is fixed by freeing the port after the
> connector.
>
> This fixes a regression introduced with
> 6b8eeca65b18ae77e175cc2b6571731f0ee413bf
> "drm/dp/mst: close deadlock in connector destruction."
>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Jani, can you please pick this up for topic/drm-fixes since Dave's still
on vacation this week?
-Daniel
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 19 +++++++++++++------
> include/drm/drm_crtc.h | 2 --
> 2 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index b0487c9f018c..eb603f1defc2 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -873,9 +873,10 @@ static void drm_dp_destroy_port(struct kref *kref)
> from an EDID retrieval */
> if (port->connector) {
> mutex_lock(&mgr->destroy_connector_lock);
> - list_add(&port->connector->destroy_list, &mgr->destroy_connector_list);
> + list_add(&port->next, &mgr->destroy_connector_list);
> mutex_unlock(&mgr->destroy_connector_lock);
> schedule_work(&mgr->destroy_connector_work);
> + return;
> }
> drm_dp_port_teardown_pdt(port, port->pdt);
>
> @@ -2659,7 +2660,7 @@ static void drm_dp_tx_work(struct work_struct *work)
> static void drm_dp_destroy_connector_work(struct work_struct *work)
> {
> struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, destroy_connector_work);
> - struct drm_connector *connector;
> + struct drm_dp_mst_port *port;
>
> /*
> * Not a regular list traverse as we have to drop the destroy
> @@ -2668,15 +2669,21 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
> */
> for (;;) {
> mutex_lock(&mgr->destroy_connector_lock);
> - connector = list_first_entry_or_null(&mgr->destroy_connector_list, struct drm_connector, destroy_list);
> - if (!connector) {
> + port = list_first_entry_or_null(&mgr->destroy_connector_list, struct drm_dp_mst_port, next);
> + if (!port) {
> mutex_unlock(&mgr->destroy_connector_lock);
> break;
> }
> - list_del(&connector->destroy_list);
> + list_del(&port->next);
> mutex_unlock(&mgr->destroy_connector_lock);
>
> - mgr->cbs->destroy_connector(mgr, connector);
> + mgr->cbs->destroy_connector(mgr, port->connector);
> +
> + drm_dp_port_teardown_pdt(port, port->pdt);
> +
> + if (!port->input && port->vcpi.vcpi > 0)
> + drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
> + kfree(port);
> }
> }
>
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 574656965126..373b1bc6de96 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -745,8 +745,6 @@ struct drm_connector {
> uint8_t num_h_tile, num_v_tile;
> uint8_t tile_h_loc, tile_v_loc;
> uint16_t tile_h_size, tile_v_size;
> -
> - struct list_head destroy_list;
> };
>
> /**
> --
> 2.1.0
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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