On Wed, May 30, 2018 at 03:42:59AM +0300, Haneen Mohammed wrote:

This patch add checks for NULL drm_[connector/crtc/plane]_helper_funcs pointers before derefrencing the variable to avoid NULL pointer dereference and make the helper functions optional in the following cases:

1. when using drm_helper_probe_single_connector_modes for fill_modes

callback in the drm_connector_funcs. 2) using drm_atomic_helper_[check/commit] for atomic_[check/commit] callbacks in the drm_mode_config_funcs.

The dependency is as follow:

drm_connector_funcs:

• fill_modes = drm_helper_probe_single_connector_modes b) drm_helper_probe_detect -> drm_connector_helper_funcs

drm_mode_config_funcs:

• atomic_check = drm_atomic_helper_check a) drm_atomic_helper_check_modeset -> drm_connector helper_funcs a) handle_conflicting_encoders -> drm_connector_helper_funcs b) mode_fixup -> drm_crtc_helper_funcs c) update_connector_routing -> drm_connectot_helper_funcs

• atomic_commit = drm_atomic_helper_commit a) drm_atomic_helper_prepare_planes -> drm_plane_helper_funcs b) drm_atomic_helper_cleanup_planes -> drm_plane_helper_funcs

Signed-off-by: Haneen Mohammed hamohammed.sa@gmail.com

Ok, I think making drm_connector_helper_funcs optional makes some sense - ->best_connector has a default implemenation that works for almost everyone, and if you don't have a way to detect the output it's silly to have a default implementation that does nothing.

But making the plane/crtc funcs optional gives you a driver which does exactly nothing, and that's not terribly useful.

I think respinning this to just make drm_connector_helper_funcs optional is reasonable, and for all others we need to start making vkms functional :-)

Cheers, Daniel

---

Chanes in v2:

• add the least amount of checks to make the helpers optional for vkms

drivers/gpu/drm/drm_atomic_helper.c | 16 ++++++++-------- drivers/gpu/drm/drm_probe_helper.c | 5 +++-- 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 2a7ceca82b9e..ff3684c4a83c 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -112,9 +112,9 @@ static int handle_conflicting_encoders(struct drm_atomic_state *state, if (!new_conn_state->crtc) continue;

• if (funcs->atomic_best_encoder)
  

• if (funcs && funcs->atomic_best_encoder)
  new_encoder = funcs->atomic_best_encoder(connector, new_conn_state);
  

• else if (funcs->best_encoder)
  

• else if (funcs && funcs->best_encoder)
  new_encoder = funcs->best_encoder(connector);
  

  else new_encoder = drm_atomic_helper_best_encoder(connector);

@@ -308,10 +308,10 @@ update_connector_routing(struct drm_atomic_state *state,

funcs = connector->helper_private;

• if (funcs->atomic_best_encoder)

• if (funcs && funcs->atomic_best_encoder) new_encoder = funcs->atomic_best_encoder(connector, new_connector_state);

• else if (funcs->best_encoder)

• else if (funcs && funcs->best_encoder) new_encoder = funcs->best_encoder(connector); else new_encoder = drm_atomic_helper_best_encoder(connector);

@@ -438,7 +438,7 @@ mode_fixup(struct drm_atomic_state *state) continue;

funcs = crtc->helper_private;

• if (!funcs->mode_fixup)
  

• if (!funcs || !funcs->mode_fixup)
  continue;
  
  

  ret = funcs->mode_fixup(crtc, &new_crtc_state->mode,

@@ -639,7 +639,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, new_crtc_state->connectors_changed = true; }

• if (funcs->atomic_check)
  

• if (funcs && funcs->atomic_check)
  ret = funcs->atomic_check(connector, new_connector_state);
  

  if (ret) return ret;

@@ -2117,7 +2117,7 @@ int drm_atomic_helper_prepare_planes(struct drm_device *dev,

funcs = plane->helper_private;

• if (funcs->prepare_fb) {
  

• if (funcs && funcs->prepare_fb) {
  ret = funcs->prepare_fb(plane, new_plane_state);
  if (ret)
  	goto fail;
  

@@ -2412,7 +2412,7 @@ void drm_atomic_helper_cleanup_planes(struct drm_device *dev,

funcs = plane->helper_private;

• if (funcs->cleanup_fb)
  

• if (funcs && funcs->cleanup_fb)
  funcs->cleanup_fb(plane, plane_state);
  

  }

} diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c index 527743394150..2fea54d16ebb 100644 --- a/drivers/gpu/drm/drm_probe_helper.c +++ b/drivers/gpu/drm/drm_probe_helper.c @@ -320,7 +320,7 @@ drm_helper_probe_detect(struct drm_connector *connector, if (ret) return ret;

• if (funcs->detect_ctx)

• if (funcs && funcs->detect_ctx) return funcs->detect_ctx(connector, ctx, force); else if (connector->funcs->detect) return connector->funcs->detect(connector, force);

@@ -480,7 +480,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, goto prune; }

• count = (*connector_funcs->get_modes)(connector);

• if (connector_funcs && connector_funcs->get_modes)

• count = (*connector_funcs->get_modes)(connector);
  
  

  if (count == 0 && connector->status == connector_status_connected) count = drm_add_modes_noedid(connector, 1024, 768);

-- 2.17.0