linux-kernel - [PATCH 1/6] drm/rockchip: inno-hdmi: Switch to drmm

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Message-Id: <20260122-drm-rk-fixes-v1-1-3942f185750e@collabora.com>
Date: Thu, 22 Jan 2026 01:17:34 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Sandy Huang <hjc@...k-chips.com>, 
 Heiko Stübner <heiko@...ech.de>, 
 Andy Yan <andy.yan@...k-chips.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
 Dmitry Baryshkov <lumag@...nel.org>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH 1/6] drm/rockchip: inno-hdmi: Switch to drmm_kzalloc()

Driver makes use of drmm_encoder_init() to initialize the encoder and
automatically handle the cleanup by registering drm_encoder_cleanup()
with drmm_add_action().

However, the internal structure containing the encoder part gets
allocated with devm_kzalloc(), which happens while component_bind_all()
is being called from Rockchip DRM driver.  The component framework
further ensures it is deallocated as part of releasing all the resources
claimed during bind, which is triggered from component_unbind_all().

When the reference to the DRM device gets eventually dropped via
drm_dev_put() in rockchip_drm_unbind(), drmm_encoder_alloc_release()
attempts to access the now released encoder structure, leading to
use-after-free.

Ensure driver's internal structure is still reachable on encoder cleanup
by switching from a device-managed allocation to a drm-managed one.

Fixes: 969325a2597e ("drm/rockchip: inno-hdmi: Convert to drm bridge")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
---
 drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c
index 97c20500f790..28e6fb09aae7 100644
--- a/drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c
@@ -14,6 +14,7 @@

 #include <drm/bridge/inno_hdmi.h>
 #include <drm/drm_bridge_connector.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_of.h>

 #include "rockchip_drm_drv.h"
@@ -90,7 +91,7 @@ static int inno_hdmi_rockchip_bind(struct device *dev, struct device *master, vo
 	const struct inno_hdmi_plat_data *plat_data;
 	int ret;

-	hdmi = devm_kzalloc(dev, sizeof(*hdmi), GFP_KERNEL);
+	hdmi = drmm_kzalloc(drm, sizeof(*hdmi), GFP_KERNEL);
 	if (!hdmi)
 		return -ENOMEM;

-- 
2.52.0