[PATCH v2 0/2] drm/meson: Fix refcount leak

[PATCH v2 0/2] drm/meson: Fix refcount leak

[Miaoqian Lin]

The following patchset fix two refcount leak bugs.
The cause of the bugs are missing of_node_put() 
after of_graph_get_remote_node().

changes in v2:
- patch#2:Fixed patch in meson_encoder_hdmi_init, call of_node_put() 
  after of_find_device_by_node() and error paths before that. 
  noted by Martin Blumenstingl <martin.blumenstingl@googlemail.com>

(patch#1: no changes since v1)

v1 link:
patch#1: https://lore.kernel.org/r/20220531144818.26943-1-linmq006@gmail.com/ 
patch#2: https://lore.kernel.org/r/20220531144818.26943-2-linmq006@gmail.com/


Miaoqian Lin (2):
  drm/meson: encoder_cvbs: Fix refcount leak in meson_encoder_cvbs_init
  drm/meson: encoder_hdmi: Fix refcount leak in meson_encoder_hdmi_init

 drivers/gpu/drm/meson/meson_encoder_cvbs.c |  1 +
 drivers/gpu/drm/meson/meson_encoder_hdmi.c | 15 +++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

-- 
2.25.1

[PATCH v2 1/2] drm/meson: encoder_cvbs: Fix refcount leak in meson_encoder_cvbs_init

[Miaoqian Lin]

of_graph_get_remote_node() returns remote device nodepointer with
refcount incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: 318ba02cd8a8 ("drm/meson: encoder_cvbs: switch to bridge with ATTACH_NO_CONNECTOR")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 drivers/gpu/drm/meson/meson_encoder_cvbs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/meson/meson_encoder_cvbs.c b/drivers/gpu/drm/meson/meson_encoder_cvbs.c
index fd8db97ba8ba..8110a6e39320 100644
--- a/drivers/gpu/drm/meson/meson_encoder_cvbs.c
+++ b/drivers/gpu/drm/meson/meson_encoder_cvbs.c
@@ -238,6 +238,7 @@ int meson_encoder_cvbs_init(struct meson_drm *priv)
 	}
 
 	meson_encoder_cvbs->next_bridge = of_drm_find_bridge(remote);
+	of_node_put(remote);
 	if (!meson_encoder_cvbs->next_bridge) {
 		dev_err(priv->dev, "Failed to find CVBS Connector bridge\n");
 		return -EPROBE_DEFER;
-- 
2.25.1

Re: [PATCH v2 1/2] drm/meson: encoder_cvbs: Fix refcount leak in meson_encoder_cvbs_init

[Martin Blumenstingl]

Hello,

thank you for your patch!

On Wed, Jun 1, 2022 at 5:39 AM Miaoqian Lin <linmq006@gmail.com> wrote:
>
> of_graph_get_remote_node() returns remote device nodepointer with
> refcount incremented, we should use of_node_put() on it when done.
> Add missing of_node_put() to avoid refcount leak.
>
> Fixes: 318ba02cd8a8 ("drm/meson: encoder_cvbs: switch to bridge with ATTACH_NO_CONNECTOR")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
As far as I can tell this patch is identical to the one from v1.
Please keep my Reviewed-by from the previous version in case nothing
has changed for this specific patch:
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>


Best regards,
Martin

[PATCH v2 2/2] drm/meson: encoder_hdmi: Fix refcount leak in meson_encoder_hdmi_init

[Miaoqian Lin]

of_graph_get_remote_node() returns remote device nodepointer with
refcount incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: e67f6037ae1b ("drm/meson: split out encoder from meson_dw_hdmi")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
changes in v2:
- call of_node_put() after of_find_device_by_node() and error paths
before of_find_device_by_node();
---
 drivers/gpu/drm/meson/meson_encoder_hdmi.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_encoder_hdmi.c b/drivers/gpu/drm/meson/meson_encoder_hdmi.c
index 5e306de6f485..0d532e8e8cca 100644
--- a/drivers/gpu/drm/meson/meson_encoder_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_encoder_hdmi.c
@@ -365,7 +365,8 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 	meson_encoder_hdmi->next_bridge = of_drm_find_bridge(remote);
 	if (!meson_encoder_hdmi->next_bridge) {
 		dev_err(priv->dev, "Failed to find HDMI transceiver bridge\n");
-		return -EPROBE_DEFER;
+		ret = -EPROBE_DEFER;
+		goto err_put_node;
 	}
 
 	/* HDMI Encoder Bridge */
@@ -383,7 +384,7 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 				      DRM_MODE_ENCODER_TMDS);
 	if (ret) {
 		dev_err(priv->dev, "Failed to init HDMI encoder: %d\n", ret);
-		return ret;
+		goto err_put_node;
 	}
 
 	meson_encoder_hdmi->encoder.possible_crtcs = BIT(0);
@@ -393,7 +394,7 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret) {
 		dev_err(priv->dev, "Failed to attach bridge: %d\n", ret);
-		return ret;
+		goto err_put_node;
 	}
 
 	/* Initialize & attach Bridge Connector */
@@ -401,7 +402,8 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 							&meson_encoder_hdmi->encoder);
 	if (IS_ERR(meson_encoder_hdmi->connector)) {
 		dev_err(priv->dev, "Unable to create HDMI bridge connector\n");
-		return PTR_ERR(meson_encoder_hdmi->connector);
+		ret = PTR_ERR(meson_encoder_hdmi->connector);
+		goto err_put_node;
 	}
 	drm_connector_attach_encoder(meson_encoder_hdmi->connector,
 				     &meson_encoder_hdmi->encoder);
@@ -428,6 +430,7 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 	meson_encoder_hdmi->connector->ycbcr_420_allowed = true;
 
 	pdev = of_find_device_by_node(remote);
+	of_node_put(remote);
 	if (pdev) {
 		struct cec_connector_info conn_info;
 		struct cec_notifier *notifier;
@@ -444,4 +447,8 @@ int meson_encoder_hdmi_init(struct meson_drm *priv)
 	dev_dbg(priv->dev, "HDMI encoder initialized\n");
 
 	return 0;
+
+err_put_node:
+	of_node_put(remote);
+	return ret;
 }
-- 
2.25.1

Re: [PATCH v2 2/2] drm/meson: encoder_hdmi: Fix refcount leak in meson_encoder_hdmi_init

[Martin Blumenstingl]

Hello,

thank you for working on this!

On Wed, Jun 1, 2022 at 5:40 AM Miaoqian Lin <linmq006@gmail.com> wrote:
>
> of_graph_get_remote_node() returns remote device nodepointer with
> refcount incremented, we should use of_node_put() on it when done.
> Add missing of_node_put() to avoid refcount leak.
>
> Fixes: e67f6037ae1b ("drm/meson: split out encoder from meson_dw_hdmi")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Note to self: at first I thought the following code needs to be changed as well:
  notifier = cec_notifier_conn_register(&pdev->dev, NULL, &conn_info);
  if (!notifier)
    return -ENOMEM;
But a few lines before this we already have:
of_node_put(remote);
Meaning: this patch is fine as is.


Best regards,
Martin

Re: [PATCH v2 0/2] drm/meson: Fix refcount leak

[Neil Armstrong]

Hi,

On Wed, 1 Jun 2022 07:39:25 +0400, Miaoqian Lin wrote:
> The following patchset fix two refcount leak bugs.
> The cause of the bugs are missing of_node_put()
> after of_graph_get_remote_node().
> 
> changes in v2:
> - patch#2:Fixed patch in meson_encoder_hdmi_init, call of_node_put()
>   after of_find_device_by_node() and error paths before that.
>   noted by Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> 
> [...]

Thanks, Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-next)

[1/2] drm/meson: encoder_cvbs: Fix refcount leak in meson_encoder_cvbs_init
      https://cgit.freedesktop.org/drm/drm-misc/commit/?id=7d255ddbbf679aa47e041cbf68520fd985ed2279
[2/2] drm/meson: encoder_hdmi: Fix refcount leak in meson_encoder_hdmi_init
      https://cgit.freedesktop.org/drm/drm-misc/commit/?id=d82a5a4aae9d0203234737caed1bf470aa317568

-- 
Neil