This patch add checks for NULL drm_connector_helper_funcs pointers before derefrencing the variable to avoid NULL pointer dereference and make the helper function 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 for atomic_check 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_mode_config_func: * atomic_check = drm_atomic_helper_check a) drm_atomic_helper_check_modeset a) handle_conflicting_encoders c) update_connector_routing

Signed-off-by: Haneen Mohammed hamohammed.sa@gmail.com --- Changes in v3: - add checks for drm_connector_helper_funcs only since plane/crtc helper funcs are necessary for a functional driver

Changes in v2: - add the least amount of checks to make the helpers optional for vkms

drivers/gpu/drm/drm_atomic_helper.c | 10 +++++----- drivers/gpu/drm/drm_probe_helper.c | 5 +++-- 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 2a7ceca82b9e..065e7fe1f979 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); @@ -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; 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);