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 <redacted>
---
 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