drm/bridge: properly refcount DT nodes in aux bridge drivers

The aux-bridge and aux-hpd-bridge drivers didn't call of_node_get() on
the device nodes further used for dev->of_node and platform data. When
bridge devices are released, the reference counts are decreased,
resulting in refcount underflow / use-after-free warnings. Get
corresponding refcounts during AUX bridge allocation.

Reported-by: Luca Weiss <luca.weiss@fairphone.com>
Fixes: 2a04739139b2 ("drm/bridge: add transparent bridge helper")
Fixes: 26f4bac3d884 ("drm/bridge: aux-hpd: Replace of_device.h with explicit include")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231216235910.911958-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/bridge/aux-bridge.c b/drivers/gpu/drm/bridge/aux-bridge.c
index 49d7c2ab1ecc39a1d3a03a4c3d137bd0ce777aee..b29980f95379ec7af873ed6e0fb79a9abb663c7b 100644 (file)
--- a/drivers/gpu/drm/bridge/aux-bridge.c
+++ b/drivers/gpu/drm/bridge/aux-bridge.c
@@ -6,6 +6,7 @@
  */
 #include <linux/auxiliary_bus.h>
 #include <linux/module.h>
+#include <linux/of.h>
 
 #include <drm/drm_bridge.h>
 #include <drm/bridge/aux-bridge.h>
@@ -57,7 +58,7 @@ int drm_aux_bridge_register(struct device *parent)
        adev->id = ret;
        adev->name = "aux_bridge";
        adev->dev.parent = parent;
-       adev->dev.of_node = parent->of_node;
+       adev->dev.of_node = of_node_get(parent->of_node);
        adev->dev.release = drm_aux_bridge_release;
 
        ret = auxiliary_device_init(adev);

diff --git a/drivers/gpu/drm/bridge/aux-hpd-bridge.c b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
index 1999a053d59bd842c679aefe841c71360ba5f3d7..bb55f697a1819264e1320f6118d28dd776236f4f 100644 (file)
--- a/drivers/gpu/drm/bridge/aux-hpd-bridge.c
+++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
@@ -68,9 +68,9 @@ struct device *drm_dp_hpd_bridge_register(struct device *parent,
        adev->id = ret;
        adev->name = "dp_hpd_bridge";
        adev->dev.parent = parent;
-       adev->dev.of_node = parent->of_node;
+       adev->dev.of_node = of_node_get(parent->of_node);
        adev->dev.release = drm_aux_hpd_bridge_release;
-       adev->dev.platform_data = np;
+       adev->dev.platform_data = of_node_get(np);
 
        ret = auxiliary_device_init(adev);
        if (ret) {