From 6914968a0b52507bf19d85e5fb9e35272e17cd35 Mon Sep 17 00:00:00 2001
From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Sun, 17 Dec 2023 01:59:10 +0200
Subject: [PATCH] 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>
---
drivers/gpu/drm/bridge/aux-bridge.c | 3 ++-
drivers/gpu/drm/bridge/aux-hpd-bridge.c | 4 ++--
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/bridge/aux-bridge.c b/drivers/gpu/drm/bridge/aux-bridge.c
index 49d7c2ab1ecc3..b29980f95379e 100644
--- 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 1999a053d59bd..bb55f697a1819 100644
--- 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) {
--
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