On Fri, May 25, 2018 at 05:20:08AM +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 as optional as possible.
>
> Signed-off-by: Haneen Mohammed <hamohammed.sa@xxxxxxxxx>
I started reviewing this, and then realized it's a bit a can of worms.
E.g. connector->funcs->detect shouldn't be there, it's a helper callback
really (but placed in the wrong function table). So connector->funcs isn't
optional, but connector->funcs->detect maybe should be optional.
So I'm not sure anymore whether doing this holesale is a good idea. Do we
still need this for vkms? If yes, then a more focused patch to just make
the things optional that vkms does not (yet) provide might be better.
Including an explanation of what exactly blows up in vkms.
Thanks, Daniel
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 42 +++++++++++++++--------------
> drivers/gpu/drm/drm_probe_helper.c | 11 ++++----
> 2 files changed, 28 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index c35654591c12..52092deb741d 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;
> @@ -681,7 +681,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> if (connectors_mask & BIT(i))
> continue;
>
> - if (funcs->atomic_check)
> + if (funcs && funcs->atomic_check)
> ret = funcs->atomic_check(connector, new_connector_state);
> if (ret)
> return ret;
> @@ -972,14 +972,16 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
>
>
> /* Right function depends upon target state. */
> - if (new_crtc_state->enable && funcs->prepare)
> - funcs->prepare(crtc);
> - else if (funcs->atomic_disable)
> - funcs->atomic_disable(crtc, old_crtc_state);
> - else if (funcs->disable)
> - funcs->disable(crtc);
> - else
> - funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
> + if (funcs) {
> + if (new_crtc_state->enable && funcs->prepare)
> + funcs->prepare(crtc);
> + else if (funcs->atomic_disable)
> + funcs->atomic_disable(crtc, old_crtc_state);
> + else if (funcs->disable)
> + funcs->disable(crtc);
> + else
> + funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
> + }
>
> if (!(dev->irq_enabled && dev->num_crtcs))
> continue;
> @@ -1093,7 +1095,7 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
>
> funcs = crtc->helper_private;
>
> - if (new_crtc_state->enable && funcs->mode_set_nofb) {
> + if (new_crtc_state->enable && funcs && funcs->mode_set_nofb) {
> DRM_DEBUG_ATOMIC("modeset on [CRTC:%d:%s]\n",
> crtc->base.id, crtc->name);
>
> @@ -1197,7 +1199,7 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
>
> funcs = crtc->helper_private;
>
> - if (new_crtc_state->enable) {
> + if (funcs && new_crtc_state->enable) {
> DRM_DEBUG_ATOMIC("enabling [CRTC:%d:%s]\n",
> crtc->base.id, crtc->name);
>
> @@ -2117,7 +2119,7 @@ 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;
> @@ -2135,7 +2137,7 @@ int drm_atomic_helper_prepare_planes(struct drm_device *dev,
>
> funcs = plane->helper_private;
>
> - if (funcs->cleanup_fb)
> + if (funcs && funcs->cleanup_fb)
> funcs->cleanup_fb(plane, new_plane_state);
> }
>
> @@ -2412,7 +2414,7 @@ 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..42507aa7f763 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -272,9 +272,9 @@ drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
> retry:
> ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
> if (!ret) {
> - if (funcs->detect_ctx)
> + if (funcs && funcs->detect_ctx)
> ret = funcs->detect_ctx(connector, &ctx, force);
> - else if (connector->funcs->detect)
> + else if (connector->funcs && connector->funcs->detect)
> ret = connector->funcs->detect(connector, force);
> else
> ret = connector_status_connected;
> @@ -320,9 +320,9 @@ 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)
> + else if (connector->funcs && connector->funcs->detect)
> return connector->funcs->detect(connector, force);
> else
> return connector_status_connected;
> @@ -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
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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