[Intel-gfx] [RFC PATCH 17/20] drm/i915/display: Fix a use-after-free when intel_edp_init_connector fails

[Matthew Brost <matthew.brost@intel.com>]

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

We enable the DP aux channel during probe, but may free the connector
soon afterwards. Ensure the DP aux display power put is completed before
everything is freed, to prevent a use-after-free in icl_aux_pw_to_phy(),
called from icl_combo_phy_aux_power_well_disable.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_power.c | 2 +-
 drivers/gpu/drm/i915/display/intel_display_power.h | 1 +
 drivers/gpu/drm/i915/display/intel_dp_aux.c        | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index fd0fedb65e42..cdb36e3f96cd 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -786,7 +786,7 @@ void intel_display_power_flush_work(struct drm_i915_private *i915)
  * Like intel_display_power_flush_work(), but also ensure that the work
  * handler function is not running any more when this function returns.
  */
-static void
+void
 intel_display_power_flush_work_sync(struct drm_i915_private *i915)
 {
 	struct i915_power_domains *power_domains = &i915->display.power.domains;
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 2154d900b1aa..d220f6b16e00 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -195,6 +195,7 @@ void __intel_display_power_put_async(struct drm_i915_private *i915,
 				     enum intel_display_power_domain domain,
 				     intel_wakeref_t wakeref);
 void intel_display_power_flush_work(struct drm_i915_private *i915);
+void intel_display_power_flush_work_sync(struct drm_i915_private *i915);
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 void intel_display_power_put(struct drm_i915_private *dev_priv,
 			     enum intel_display_power_domain domain,
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 91c93c93e5fc..220aa88c67ee 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -680,6 +680,8 @@ void intel_dp_aux_fini(struct intel_dp *intel_dp)
 	if (cpu_latency_qos_request_active(&intel_dp->pm_qos))
 		cpu_latency_qos_remove_request(&intel_dp->pm_qos);
 
+	/* Ensure async work from intel_dp_aux_xfer() is flushed before we clean up */
+	intel_display_power_flush_work_sync(dp_to_i915(intel_dp));
 	kfree(intel_dp->aux.name);
 }
 
-- 
2.37.3