[PATCH v2 0/8] Rockchip DRM use-after-free & null-ptr-deref fixes

[PATCH v2 0/8] Rockchip DRM use-after-free & null-ptr-deref fixes

[Cristian Ciocaltea]

The first three patches in the series are fixes for use-after-free &
null-ptr-deref related issues found in dw_dp and inno-hdmi Rockchip DRM
drivers.

The following three patches provide a few minor improvements to dw_dp
and dw_hdmi_qp, while the remaining two address use-after-free and
memory allocation in DW DP core library.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
Changes in v2:
- Fixed conflicts while rebasing onto latest drm-misc-next
- Added two more patches:
 * drm/bridge: synopsys: dw-dp: Unregister AUX channel on bridge detach
 * drm/bridge: synopsys: dw-dp: Drop useless memory allocation
- Link to v1: https://lore.kernel.org/r/20260122-drm-rk-fixes-v1-0-3942f185750e@collabora.com

---
Cristian Ciocaltea (8):
      drm/rockchip: inno-hdmi: Switch to drmm_kzalloc()
      drm/rockchip: dw_dp: Switch to drmm_kzalloc()
      drm/rockchip: dw_dp: Fix null-ptr-deref in dw_dp_remove()
      drm/rockchip: dw_dp: Simplify error handling
      drm/rockchip: dw_dp: Drop unnecessary #include
      drm/rockchip: dw_hdmi_qp: Switch to drmm_encoder_init()
      drm/bridge: synopsys: dw-dp: Unregister AUX channel on bridge detach
      drm/bridge: synopsys: dw-dp: Drop useless memory allocation

 drivers/gpu/drm/bridge/synopsys/dw-dp.c        | 12 ++++++---
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c      | 35 ++++++++++----------------
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 13 +++++-----
 drivers/gpu/drm/rockchip/inno_hdmi-rockchip.c  |  3 ++-
 4 files changed, 29 insertions(+), 34 deletions(-)
---
base-commit: bfb18fd193e2413f02ad934e46887f415f0ce4ec
change-id: 20260122-drm-rk-fixes-a7622c71553e

[PATCH v2 1/8] drm/rockchip: inno-hdmi: Switch to drmm_kzalloc()

[Cristian Ciocaltea]

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@collabora.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

[PATCH v2 2/8] drm/rockchip: dw_dp: Switch to drmm_kzalloc()

[Cristian Ciocaltea]

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: d68ba7bac955 ("drm/rockchip: Add RK3588 DPTX output support")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
index dac3d202971e..532af476d250 100644
--- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
@@ -13,6 +13,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_bridge_connector.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_of.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
@@ -82,7 +83,7 @@ static int dw_dp_rockchip_bind(struct device *dev, struct device *master, void *
 	struct drm_connector *connector;
 	int ret;
 
-	dp = devm_kzalloc(dev, sizeof(*dp), GFP_KERNEL);
+	dp = drmm_kzalloc(drm_dev, sizeof(*dp), GFP_KERNEL);
 	if (!dp)
 		return -ENOMEM;
 

-- 
2.52.0

[PATCH v2 3/8] drm/rockchip: dw_dp: Fix null-ptr-deref in dw_dp_remove()

[Cristian Ciocaltea]

Attempting to access driver data in the platform driver ->remove()
callback may lead to a null pointer dereference since there is no
guaranty that the component ->bind() callback invoking
platform_set_drvdata() was executed.

A common scenario is when Rockchip DRM driver didn't manage to run
component_bind_all() because of an (unrelated) error causing early
return from rockchip_drm_bind().

Drop the unnecessary call to platform_get_drvdata() and, instead,
reference the target device structure via platform_device.

Fixes: d68ba7bac955 ("drm/rockchip: Add RK3588 DPTX output support")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
index 532af476d250..8945a245398c 100644
--- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
@@ -133,9 +133,7 @@ static int dw_dp_probe(struct platform_device *pdev)
 
 static void dw_dp_remove(struct platform_device *pdev)
 {
-	struct rockchip_dw_dp *dp = platform_get_drvdata(pdev);
-
-	component_del(dp->dev, &dw_dp_rockchip_component_ops);
+	component_del(&pdev->dev, &dw_dp_rockchip_component_ops);
 }
 
 static const struct dw_dp_plat_data rk3588_dp_plat_data = {

-- 
2.52.0

[PATCH v2 4/8] drm/rockchip: dw_dp: Simplify error handling

[Cristian Ciocaltea]

Make the code a bit more compact by getting rid of the superfluous
assignments around PTR_ERR().

While at it, also drop dev assignment in dw_dp_probe().

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
index 8945a245398c..fafefee8370d 100644
--- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
@@ -104,20 +104,15 @@ static int dw_dp_rockchip_bind(struct device *dev, struct device *master, void *
 	drm_encoder_helper_add(encoder, &dw_dp_encoder_helper_funcs);
 
 	dp->base = dw_dp_bind(dev, encoder, plat_data);
-	if (IS_ERR(dp->base)) {
-		ret = PTR_ERR(dp->base);
-		return ret;
-	}
+	if (IS_ERR(dp->base))
+		return PTR_ERR(dp->base);
 
 	connector = drm_bridge_connector_init(drm_dev, encoder);
-	if (IS_ERR(connector)) {
-		ret = PTR_ERR(connector);
-		return dev_err_probe(dev, ret, "Failed to init bridge connector");
-	}
+	if (IS_ERR(connector))
+		return dev_err_probe(dev, PTR_ERR(connector),
+				     "Failed to init bridge connector");
 
-	drm_connector_attach_encoder(connector, encoder);
-
-	return 0;
+	return drm_connector_attach_encoder(connector, encoder);
 }
 
 static const struct component_ops dw_dp_rockchip_component_ops = {
@@ -126,9 +121,7 @@ static const struct component_ops dw_dp_rockchip_component_ops = {
 
 static int dw_dp_probe(struct platform_device *pdev)
 {
-	struct device *dev = &pdev->dev;
-
-	return component_add(dev, &dw_dp_rockchip_component_ops);
+	return component_add(&pdev->dev, &dw_dp_rockchip_component_ops);
 }
 
 static void dw_dp_remove(struct platform_device *pdev)

-- 
2.52.0

[PATCH v2 5/8] drm/rockchip: dw_dp: Drop unnecessary #include

[Cristian Ciocaltea]

Included header "rockchip_drm_vop.h" is not directly used, drop it.

While at it, ensure #include directives are ordered alphabetically.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_dp-rockchip.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
index fafefee8370d..22c0911f1896 100644
--- a/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_dp-rockchip.c
@@ -7,8 +7,11 @@
  */
 
 #include <linux/component.h>
+#include <linux/media-bus-format.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/videodev2.h>
+
 #include <drm/bridge/dw_dp.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
@@ -19,11 +22,7 @@
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_simple_kms_helper.h>
 
-#include <linux/media-bus-format.h>
-#include <linux/videodev2.h>
-
 #include "rockchip_drm_drv.h"
-#include "rockchip_drm_vop.h"
 
 struct rockchip_dw_dp {
 	struct dw_dp *base;

-- 
2.52.0

[PATCH v2 6/8] drm/rockchip: dw_hdmi_qp: Switch to drmm_encoder_init()

[Cristian Ciocaltea]

Simplify encoder initialization and cleanup by making use of
drmm_encoder_init(), which takes care of registering
drm_encoder_cleanup() with drmm_add_action().

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index 1a09bcc96c3e..c78db7f8ab6c 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -21,6 +21,7 @@
 #include <drm/bridge/dw_hdmi_qp.h>
 #include <drm/display/drm_hdmi_helper.h>
 #include <drm/drm_bridge_connector.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_of.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_simple_kms_helper.h>
@@ -477,7 +478,7 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 	if (!pdev->dev.of_node)
 		return -ENODEV;
 
-	hdmi = devm_kzalloc(&pdev->dev, sizeof(*hdmi), GFP_KERNEL);
+	hdmi = drmm_kzalloc(drm, sizeof(*hdmi), GFP_KERNEL);
 	if (!hdmi)
 		return -ENOMEM;
 
@@ -586,16 +587,16 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 		return ret;
 
 	drm_encoder_helper_add(encoder, &dw_hdmi_qp_rockchip_encoder_helper_funcs);
-	drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
+	ret = drmm_encoder_init(drm, encoder, NULL, DRM_MODE_ENCODER_TMDS, NULL);
+	if (ret)
+		return dev_err_probe(hdmi->dev, ret, "Failed to init encoder");
 
 	platform_set_drvdata(pdev, hdmi);
 
 	hdmi->hdmi = dw_hdmi_qp_bind(pdev, encoder, &plat_data);
-	if (IS_ERR(hdmi->hdmi)) {
-		drm_encoder_cleanup(encoder);
+	if (IS_ERR(hdmi->hdmi))
 		return dev_err_probe(hdmi->dev, PTR_ERR(hdmi->hdmi),
 				     "Failed to bind dw-hdmi-qp");
-	}
 
 	connector = drm_bridge_connector_init(drm, encoder);
 	if (IS_ERR(connector))
@@ -612,8 +613,6 @@ static void dw_hdmi_qp_rockchip_unbind(struct device *dev,
 	struct rockchip_hdmi_qp *hdmi = dev_get_drvdata(dev);
 
 	cancel_delayed_work_sync(&hdmi->hpd_work);
-
-	drm_encoder_cleanup(&hdmi->encoder.encoder);
 }
 
 static const struct component_ops dw_hdmi_qp_rockchip_ops = {

-- 
2.52.0

[PATCH v2 7/8] drm/bridge: synopsys: dw-dp: Unregister AUX channel on bridge detach

[Cristian Ciocaltea]

The DisplayPort AUX channel gets initialized and registered during
dw_dp_bind(), but it is never unregistered, which may lead to resource
leaks and/or use-after-free:

[  224.661371] BUG: KASAN: slab-use-after-free in device_is_dependent+0xe0/0x2b0
[  224.662015] Read of size 8 at addr ffff00011aee8550 by task modprobe/658
...
[  224.662796]  device_is_dependent+0xe0/0x2b0
[  224.662802]  device_is_dependent+0x108/0x2b0
[  224.662808]  device_link_add+0x1f8/0x10b0
[  224.662813]  devm_of_phy_get_by_index+0x120/0x200
[  224.662819]  dw_dp_bind+0x34c/0xb10 [dw_dp]
[  224.662830]  dw_dp_rockchip_bind+0x194/0x250 [rockchipdrm]
[  224.662864]  component_bind_all+0x3a8/0x720
[  224.662869]  rockchip_drm_bind+0x120/0x390 [rockchipdrm]
[  224.662899]  try_to_bring_up_aggregate_device+0x76c/0x838
[  224.662904]  component_master_add_with_match+0x1f4/0x230
[  224.662909]  rockchip_drm_platform_probe+0x420/0x538 [rockchipdrm]
[  224.662939]  platform_probe+0xe8/0x168
[  224.662945]  really_probe+0x340/0x828
[  224.662950]  __driver_probe_device+0x2e0/0x350
[  224.662954]  driver_probe_device+0x80/0x140
[  224.662959]  __driver_attach+0x398/0x460
[  224.662964]  bus_for_each_dev+0xe0/0x198
[  224.662968]  driver_attach+0x50/0x68
[  224.662972]  bus_add_driver+0x2a0/0x4c0
[  224.662977]  driver_register+0x294/0x360
[  224.662982]  __platform_driver_register+0x7c/0x98
[  224.662987]  rockchip_drm_init+0xc4/0xff8 [rockchipdrm]
...

Unregister the AUX adapter on bridge detach.

Fixes: 86eecc3a9c2e ("drm/bridge: synopsys: Add DW DPTX Controller support library")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index e7bef9150f6a..8d02f047693a 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -1751,6 +1751,13 @@ static const struct drm_edid *dw_dp_bridge_edid_read(struct drm_bridge *bridge,
 	return edid;
 }
 
+static void dw_dp_bridge_detach(struct drm_bridge *bridge)
+{
+	struct dw_dp *dp = bridge_to_dp(bridge);
+
+	drm_dp_aux_unregister(&dp->aux);
+}
+
 static u32 *dw_dp_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
 						    struct drm_bridge_state *bridge_state,
 						    struct drm_crtc_state *crtc_state,
@@ -1824,6 +1831,7 @@ static const struct drm_bridge_funcs dw_dp_bridge_funcs = {
 	.atomic_disable = dw_dp_bridge_atomic_disable,
 	.detect = dw_dp_bridge_detect,
 	.edid_read = dw_dp_bridge_edid_read,
+	.detach = dw_dp_bridge_detach,
 };
 
 static int dw_dp_link_retrain(struct dw_dp *dp)

-- 
2.52.0

Re: [PATCH v2 7/8] drm/bridge: synopsys: dw-dp: Unregister AUX channel on bridge detach

[Heiko Stuebner]

Am Montag, 9. März 2026, 23:44:35 Mitteleuropäische Normalzeit schrieb Cristian Ciocaltea:
> The DisplayPort AUX channel gets initialized and registered during
> dw_dp_bind(), but it is never unregistered, which may lead to resource
> leaks and/or use-after-free:
> 
> [  224.661371] BUG: KASAN: slab-use-after-free in device_is_dependent+0xe0/0x2b0
> [  224.662015] Read of size 8 at addr ffff00011aee8550 by task modprobe/658
> ...
> [  224.662796]  device_is_dependent+0xe0/0x2b0
> [  224.662802]  device_is_dependent+0x108/0x2b0
> [  224.662808]  device_link_add+0x1f8/0x10b0
> [  224.662813]  devm_of_phy_get_by_index+0x120/0x200
> [  224.662819]  dw_dp_bind+0x34c/0xb10 [dw_dp]
> [  224.662830]  dw_dp_rockchip_bind+0x194/0x250 [rockchipdrm]
> [  224.662864]  component_bind_all+0x3a8/0x720
> [  224.662869]  rockchip_drm_bind+0x120/0x390 [rockchipdrm]
> [  224.662899]  try_to_bring_up_aggregate_device+0x76c/0x838
> [  224.662904]  component_master_add_with_match+0x1f4/0x230
> [  224.662909]  rockchip_drm_platform_probe+0x420/0x538 [rockchipdrm]
> [  224.662939]  platform_probe+0xe8/0x168
> [  224.662945]  really_probe+0x340/0x828
> [  224.662950]  __driver_probe_device+0x2e0/0x350
> [  224.662954]  driver_probe_device+0x80/0x140
> [  224.662959]  __driver_attach+0x398/0x460
> [  224.662964]  bus_for_each_dev+0xe0/0x198
> [  224.662968]  driver_attach+0x50/0x68
> [  224.662972]  bus_add_driver+0x2a0/0x4c0
> [  224.662977]  driver_register+0x294/0x360
> [  224.662982]  __platform_driver_register+0x7c/0x98
> [  224.662987]  rockchip_drm_init+0xc4/0xff8 [rockchipdrm]
> ...
> 
> Unregister the AUX adapter on bridge detach.

that sounds sort of asymmetrical though. drm_bridge_funcs has attach and
detach callbacks and the component-framework also has bind and unbind
callbacks.

This might cause confusion later on I guess, especially as I don't know
if there could be a bridge attach, after the detach that unregisters the
aux adapter.

Looking at the AnalogixDP for example, it does the the register and
unregister in the bind/unbind callbacks of the core driver.

So I guess the in my eyes cleaner way would be to introduce a
dw_dp_unbind() function and put the aux unregister there?

At least that way, everything would be at the same "level".


Heiko

Re: [PATCH v2 7/8] drm/bridge: synopsys: dw-dp: Unregister AUX channel on bridge detach

[Cristian Ciocaltea]

Hello Heiko,

On 3/26/26 9:28 PM, Heiko Stuebner wrote:
> Am Montag, 9. März 2026, 23:44:35 Mitteleuropäische Normalzeit schrieb Cristian Ciocaltea:
>> The DisplayPort AUX channel gets initialized and registered during
>> dw_dp_bind(), but it is never unregistered, which may lead to resource
>> leaks and/or use-after-free:
>>
>> [  224.661371] BUG: KASAN: slab-use-after-free in device_is_dependent+0xe0/0x2b0
>> [  224.662015] Read of size 8 at addr ffff00011aee8550 by task modprobe/658
>> ...
>> [  224.662796]  device_is_dependent+0xe0/0x2b0
>> [  224.662802]  device_is_dependent+0x108/0x2b0
>> [  224.662808]  device_link_add+0x1f8/0x10b0
>> [  224.662813]  devm_of_phy_get_by_index+0x120/0x200
>> [  224.662819]  dw_dp_bind+0x34c/0xb10 [dw_dp]
>> [  224.662830]  dw_dp_rockchip_bind+0x194/0x250 [rockchipdrm]
>> [  224.662864]  component_bind_all+0x3a8/0x720
>> [  224.662869]  rockchip_drm_bind+0x120/0x390 [rockchipdrm]
>> [  224.662899]  try_to_bring_up_aggregate_device+0x76c/0x838
>> [  224.662904]  component_master_add_with_match+0x1f4/0x230
>> [  224.662909]  rockchip_drm_platform_probe+0x420/0x538 [rockchipdrm]
>> [  224.662939]  platform_probe+0xe8/0x168
>> [  224.662945]  really_probe+0x340/0x828
>> [  224.662950]  __driver_probe_device+0x2e0/0x350
>> [  224.662954]  driver_probe_device+0x80/0x140
>> [  224.662959]  __driver_attach+0x398/0x460
>> [  224.662964]  bus_for_each_dev+0xe0/0x198
>> [  224.662968]  driver_attach+0x50/0x68
>> [  224.662972]  bus_add_driver+0x2a0/0x4c0
>> [  224.662977]  driver_register+0x294/0x360
>> [  224.662982]  __platform_driver_register+0x7c/0x98
>> [  224.662987]  rockchip_drm_init+0xc4/0xff8 [rockchipdrm]
>> ...
>>
>> Unregister the AUX adapter on bridge detach.
> 
> that sounds sort of asymmetrical though. drm_bridge_funcs has attach and
> detach callbacks and the component-framework also has bind and unbind
> callbacks.
> 
> This might cause confusion later on I guess, especially as I don't know
> if there could be a bridge attach, after the detach that unregisters the
> aux adapter.
> 
> Looking at the AnalogixDP for example, it does the the register and
> unregister in the bind/unbind callbacks of the core driver.
> 
> So I guess the in my eyes cleaner way would be to introduce a
> dw_dp_unbind() function and put the aux unregister there?
> 
> At least that way, everything would be at the same "level".

You are right.  As a matter of fact exporting the *_unbind() in the library was
my first thought, but for some reason I went with the "auto" approach.

I've just handled this in v3 [1].

Thanks for reviewing and picking the rest of the patches!

Regards,
Cristian

[1] https://lore.kernel.org/all/20260327-drm-rk-fixes-v3-0-fd2e6900c08c@collabora.com/

[PATCH v2 8/8] drm/bridge: synopsys: dw-dp: Drop useless memory allocation

[Cristian Ciocaltea]

The bridge gets allocated and initialized implicitly via the
devm_drm_bridge_alloc() helper in dw_dp_bind().  However, this is
preceded by an explicit allocation for the same dw_dp struct, which is
never used anywhere as the return from devm_kzalloc() gets immediately
overwritten by the aforementioned helper.

Get rid of the unnecessary and confusing memory allocation.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 8d02f047693a..9e7ace6be3a0 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -1977,10 +1977,6 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
 	void __iomem *res;
 	int ret;
 
-	dp = devm_kzalloc(dev, sizeof(*dp), GFP_KERNEL);
-	if (!dp)
-		return ERR_PTR(-ENOMEM);
-
 	dp = devm_drm_bridge_alloc(dev, struct dw_dp, bridge, &dw_dp_bridge_funcs);
 	if (IS_ERR(dp))
 		return ERR_CAST(dp);

-- 
2.52.0

Re: (subset) [PATCH v2 0/8] Rockchip DRM use-after-free & null-ptr-deref fixes

[Heiko Stuebner]

On Tue, 10 Mar 2026 00:44:28 +0200, Cristian Ciocaltea wrote:
> The first three patches in the series are fixes for use-after-free &
> null-ptr-deref related issues found in dw_dp and inno-hdmi Rockchip DRM
> drivers.
> 
> The following three patches provide a few minor improvements to dw_dp
> and dw_hdmi_qp, while the remaining two address use-after-free and
> memory allocation in DW DP core library.
> 
> [...]

Applied, thanks!

[1/8] drm/rockchip: inno-hdmi: Switch to drmm_kzalloc()
      commit: 3cc50e7f73fcf79f28660b9d91566b13cb62e520
[2/8] drm/rockchip: dw_dp: Switch to drmm_kzalloc()
      commit: ed9da8d23020352ad24c528db09b5acdd78b81fd
[3/8] drm/rockchip: dw_dp: Fix null-ptr-deref in dw_dp_remove()
      commit: 9456381d8b60bb7dd42f2f04afe5ee4ce6e0bc12
[4/8] drm/rockchip: dw_dp: Simplify error handling
      commit: 26cb3e26efa7cc84289966cab871889f6ca93616
[5/8] drm/rockchip: dw_dp: Drop unnecessary #include
      commit: 31a98842a11fcb52a2db9b1b498d5ac11793e35f
[6/8] drm/rockchip: dw_hdmi_qp: Switch to drmm_encoder_init()
      commit: e1f7b7cbd74c6561944f5dda345dab59ad391acb
[8/8] drm/bridge: synopsys: dw-dp: Drop useless memory allocation
      commit: 971a6d5d41315f3bfe1e1207f24da9a191c949ff

Best regards,
-- 
Heiko Stuebner <heiko@sntech.de>