Unverified Commit dc2d5ddb authored by Shenghao Yang's avatar Shenghao Yang Committed by Ruben Wauters
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drm/gud: fix NULL fb and crtc dereferences on USB disconnect 



On disconnect drm_atomic_helper_disable_all() is called which
sets both the fb and crtc for a plane to NULL before invoking a commit.

This causes a kernel oops on every display disconnect.

Add guards for those dereferences.

Cc: <stable@vger.kernel.org> # 6.18.x
Fixes: 73cfd166 ("drm/gud: Replace simple display pipe with DRM atomic helpers")
Signed-off-by: default avatarShenghao Yang <me@shenghaoyang.info>
Reviewed-by: default avatarRuben Wauters <rubenru09@aol.com>
Signed-off-by: default avatarRuben Wauters <rubenru09@aol.com>
Link: https://patch.msgid.link/20251231055039.44266-1-me@shenghaoyang.info
parent 9380dc33

drivers/gpu/drm/gud/gud_pipe.c

+8 −12
Original line number Diff line number Diff line
@@ -457,28 +457,21 @@ int gud_plane_atomic_check(struct drm_plane *plane, 
	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);

	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);

	struct drm_crtc *crtc = new_plane_state->crtc;

	struct drm_crtc_state *crtc_state;

	struct drm_crtc_state *crtc_state = NULL;

	const struct drm_display_mode *mode;

	struct drm_framebuffer *old_fb = old_plane_state->fb;

	struct drm_connector_state *connector_state = NULL;

	struct drm_framebuffer *fb = new_plane_state->fb;

	const struct drm_format_info *format = fb->format;

	const struct drm_format_info *format;

	struct drm_connector *connector;

	unsigned int i, num_properties;

	struct gud_state_req *req;

	int idx, ret;

	size_t len;



	if (drm_WARN_ON_ONCE(plane->dev, !fb))

		return -EINVAL;



	if (drm_WARN_ON_ONCE(plane->dev, !crtc))

		return -EINVAL;



	if (crtc)

		crtc_state = drm_atomic_get_new_crtc_state(state, crtc);



	mode = &crtc_state->mode;



	ret = drm_atomic_helper_check_plane_state(new_plane_state, crtc_state,

						  DRM_PLANE_NO_SCALING,

						  DRM_PLANE_NO_SCALING,
@@ -492,6 +485,9 @@ int gud_plane_atomic_check(struct drm_plane *plane, 
	if (old_plane_state->rotation != new_plane_state->rotation)

		crtc_state->mode_changed = true;



	mode = &crtc_state->mode;

	format = fb->format;



	if (old_fb && old_fb->format != format)

		crtc_state->mode_changed = true;
@@ -598,7 +594,7 @@ void gud_plane_atomic_update(struct drm_plane *plane, 
	struct drm_atomic_helper_damage_iter iter;

	int ret, idx;



	if (crtc->state->mode_changed || !crtc->state->enable) {

	if (!crtc || crtc->state->mode_changed || !crtc->state->enable) {

		cancel_work_sync(&gdrm->work);

		mutex_lock(&gdrm->damage_lock);

		if (gdrm->fb) {