[PATCH 0/6] drm/rockchip: Fix error handling and resource leaks in Rockchip DRM drivers

[PATCH 0/6] drm/rockchip: Fix error handling and resource leaks in Rockchip DRM drivers

[Jiaqi]

This patch series fixes 6 bugs in the Rockchip DRM driver subsystem,
identified through static code analysis and confirmed by technical review.

The bugs range from Critical (of_node reference leaks, use-after-free)
to Medium (unchecked return values), and span 5 different source files.
Each patch addresses exactly one bug to facilitate review and bisection.

Summary of fixes:

  Patch 1/6 (Critical): Fix of_node reference leak in
    rockchip_drm_encoder_set_crtc_endpoint_id(). Both success and error
    paths leaked references acquired via of_graph helpers.

  Patch 2/6 (Critical): Fix dangling crtc->state in vop2_crtc_reset().
    kzalloc() failure left crtc->state as a use-after-free pointer.

  Patch 3/6 (High): Fix vop2_create_crtcs() error path cleanup in
    vop2_bind(). Failures returned directly without calling
    vop2_destroy_crtcs(), leaking of_node references.

  Patch 4/6 (High): Fix vmap address caching in
    rockchip_gem_prime_vmap(). New vmap() results were not saved to
    rk_obj->kvaddr, causing repeated mappings and potential leaks.

  Patch 5/6 (High): Fix leaked vblank event in
    vop_crtc_atomic_disable(). Pending vop->event was warned but never
    sent, causing userspace hangs and vblank reference leaks.

  Patch 6/6 (Medium): Check return value of cdn_dp_grf_write() in
    cdn_dp_enable_phy() error path. Ignored return value could leave
    GRF registers in an inconsistent state.

All patches have been verified against checkpatch.pl --strict.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/cdn-dp-core.c       |  5 +++--
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c  | 14 +++++++++----
 drivers/gpu/drm/rockchip/rockchip_drm_gem.c  |  1 +
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c  | 11 ++++++++++-
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 13 ++++++++++--
 5 files changed, 35 insertions(+), 9 deletions(-)
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[PATCH 1/6] drm/rockchip: Fix of_node reference leak in rockchip_drm_encoder_set_crtc_endpoint_id()

[Jiaqi]

The function rockchip_drm_encoder_set_crtc_endpoint_id() acquires device
tree node references via of_graph_get_endpoint_by_regs() and
of_graph_get_remote_endpoint(), but never releases them. This happens on
all exit paths, including the success path.

This leads to reference count leaks that accumulate during encoder probe.
In deferred probe scenarios or module reload, the leaked references can
cause of_node_get() to eventually return -ENOMEM, breaking subsequent
device tree parsing.

Fix by adding the corresponding of_node_put() calls for both 'en' and
'ren', and use a unified error path to avoid duplication.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 14 +++++++++----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -278,18 +278,22 @@ int rockchip_drm_encoder_set_crtc_endpoint_id(struct rockchip_encoder *rkencoder,
 {
 	struct of_endpoint ep;
 	struct device_node *en, *ren;
 	int ret;

 	en = of_graph_get_endpoint_by_regs(np, port, reg);
 	if (!en)
 		return -ENOENT;

 	ren = of_graph_get_remote_endpoint(en);
 	if (!ren)
-		return -ENOENT;
+		goto err_put_en;

 	ret = of_graph_parse_endpoint(ren, &ep);
 	if (ret)
-		return ret;
+		goto err_put_ren;

 	rkencoder->crtc_endpoint_id = ep.id;

-	return 0;
+err_put_ren:
+	of_node_put(ren);
+err_put_en:
+	of_node_put(en);
+	return ret;
 }

 /*
--
2.40.0
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[PATCH 2/6] drm/rockchip: Fix dangling crtc->state in vop2_crtc_reset()

[Jiaqi]

In vop2_crtc_reset(), if kzalloc() fails to allocate a new
rockchip_crtc_state, the function returns early without setting
crtc->state to NULL. However, the old state has already been destroyed
and freed by __drm_atomic_helper_crtc_destroy_state() and kfree().

This leaves crtc->state as a dangling pointer. Any subsequent access to
crtc->state (e.g., through to_rockchip_crtc_state()) will result in a
use-after-free or NULL pointer dereference, leading to a kernel crash.

Fix by setting crtc->state = NULL when kzalloc() fails, ensuring the
pointer is in a well-defined state.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -2082,8 +2082,10 @@ static void vop2_crtc_reset(struct drm_crtc *crtc)
 	}

 	vcstate = kzalloc(sizeof(*vcstate), GFP_KERNEL);
-	if (!vcstate)
+	if (!vcstate) {
+		crtc->state = NULL;
 		return;
+	}

 	crtc->state = &vcstate->base;
 	crtc->state->crtc = crtc;
--
2.40.0
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[PATCH 3/6] drm/rockchip: Fix vop2_create_crtcs() error path cleanup in vop2_bind()

[Jiaqi]

In vop2_bind(), when vop2_create_crtcs() fails, the function returns
immediately without calling vop2_destroy_crtcs(). This means any
of_node references stored in vp->crtc.port by vop2_create_crtcs() are
leaked, as they are only released in vop2_destroy_crtcs().

Additionally, if the component framework retries the bind (e.g., due to
-EPROBE_DEFER from downstream components), the previously registered
IRQ via devm_request_irq() will cause subsequent attempts to return
-EBUSY, permanently breaking the driver.

Fix by ensuring vop2_create_crtcs() failures go through the err_crtcs
label, which calls vop2_destroy_crtcs() to properly release all
resources including of_node references.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -2735,7 +2735,7 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)

 	ret = vop2_create_crtcs(vop2);
 	if (ret)
-		return ret;
+		goto err_crtcs;

 	ret = vop2_find_rgb_encoder(vop2);
 	if (ret >= 0) {
@@ -2758,8 +2758,8 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 	return 0;

 err_crtcs:
+	devm_free_irq(dev, vop2->irq, vop2);
 	vop2_destroy_crtcs(vop2);
-
 	return ret;
 }

--
2.40.0
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[PATCH 6/6] drm/rockchip: Check return value of cdn_dp_grf_write() in error path

[Jiaqi]

In cdn_dp_enable_phy(), when an error occurs after the GRF register has
been set to DPTX_HPD_SEL, the cleanup path at err_phy calls
cdn_dp_grf_write() to restore DPTX_HPD_DEL, but the return value is
ignored.

If this restore write fails (e.g., due to a bus timeout or GRF power
loss), the GRF register remains in the DPTX_HPD_SEL state. This leaves
the DP PHY control in an inconsistent state, which can cause subsequent
DP link initialization to fail or produce undefined behavior.

Fix by checking the return value of cdn_dp_grf_write() in the error
path and logging an error if it fails.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/cdn-dp-core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/cdn-dp-core.c b/drivers/gpu/drm/rockchip/cdn-dp-core.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-core.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-core.c
@@ -425,8 +425,9 @@ err_power_on:
 		port->phy_enabled = false;

 err_phy:
-	cdn_dp_grf_write(dp, GRF_SOC_CON26,
-			 DPTX_HPD_SEL_MASK | DPTX_HPD_DEL);
+	ret = cdn_dp_grf_write(dp, GRF_SOC_CON26,
+			       DPTX_HPD_SEL_MASK | DPTX_HPD_DEL);
+	if (ret)
+		DRM_DEV_ERROR(dp->dev, "Failed to restore HPD_DEL: %d\n", ret);
 	return ret;
 }

--
2.40.0
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