[PATCH] rpi_touchscreen_probe: check for failure case

[PATCH] rpi_touchscreen_probe: check for failure case

[Navid Emamdoost]

of_graph_get_next_endpoint may return NULL, so null check is needed.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 28c0620dfe0f..2e0977e26fab 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -399,6 +399,8 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 
 	/* Look up the DSI host.  It needs to probe before we do. */
 	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return -ENODEV;
 	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
 	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
 	of_node_put(dsi_host_node);
-- 
2.17.1

Re: [PATCH] rpi_touchscreen_probe: check for failure case

[Sam Ravnborg]

Hi Navid.

Thanks for your patch.
On Tue, Jul 23, 2019 at 09:56:43PM -0500, Navid Emamdoost wrote:
> of_graph_get_next_endpoint may return NULL, so null check is needed.
> 
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>

The patch looks fine, but could you please audit the other calls in the
probe function. For example of_graph_get_remote_port_parent() may also
return NULL.
If you do this then we can have the error handling reviewed in one go,
and fixed in one patch.

	Sam

> ---
>  drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> index 28c0620dfe0f..2e0977e26fab 100644
> --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -399,6 +399,8 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
>  
>  	/* Look up the DSI host.  It needs to probe before we do. */
>  	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	if (!endpoint)
> +		return -ENODEV;
>  	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
>  	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
>  	of_node_put(dsi_host_node);
> -- 
> 2.17.1

[PATCH] drm/panel: check failure cases in the probe func

[Navid Emamdoost]

The following function calls may fail and return NULL, so the null check
is added.
of_graph_get_next_endpoint
of_graph_get_remote_port_parent
of_graph_get_remote_port

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 28c0620dfe0f..9484fdb60f68 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -399,7 +399,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 
 	/* Look up the DSI host.  It needs to probe before we do. */
 	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return -ENODEV;
+
 	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		return -ENODEV;
+
 	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
 	of_node_put(dsi_host_node);
 	if (!host) {
@@ -408,6 +414,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 	}
 
 	info.node = of_graph_get_remote_port(endpoint);
+	if (!info.node)
+		return -ENODEV;
+
 	of_node_put(endpoint);
 
 	ts->dsi = mipi_dsi_device_register_full(host, &info);
-- 
2.17.1

Re: [PATCH] drm/panel: check failure cases in the probe func

[Sam Ravnborg]

Hi Navid.

Thanks for your patch.

On Wed, Jul 24, 2019 at 09:48:44AM -0500, Navid Emamdoost wrote:
> The following function calls may fail and return NULL, so the null check
> is added.
> of_graph_get_next_endpoint
> of_graph_get_remote_port_parent
> of_graph_get_remote_port
> 
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> ---
>  drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> index 28c0620dfe0f..9484fdb60f68 100644
> --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -399,7 +399,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
>  
>  	/* Look up the DSI host.  It needs to probe before we do. */
>  	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	if (!endpoint)
> +		return -ENODEV;
> +
>  	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
> +	if (!dsi_host_node)
> +		return -ENODEV;
> +
If we return here we will leak endpoint - a of_node_put() is missing.
Use goto to rewind the allocations in the bottom of this function.

>  	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
>  	of_node_put(dsi_host_node);
>  	if (!host) {
> @@ -408,6 +414,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
>  	}
>  
>  	info.node = of_graph_get_remote_port(endpoint);
> +	if (!info.node)
> +		return -ENODEV;
Here we also leak endpoint, but not dsi_host_node as we already did a
put above.

> +
>  	of_node_put(endpoint);
>  
>  	ts->dsi = mipi_dsi_device_register_full(host, &info);

	Sam
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Re: [PATCH] drm/panel: check failure cases in the probe func

[Sam Ravnborg]

Hi Navid.

Thanks for your patch.

On Wed, Jul 24, 2019 at 09:48:44AM -0500, Navid Emamdoost wrote:
> The following function calls may fail and return NULL, so the null check
> is added.
> of_graph_get_next_endpoint
> of_graph_get_remote_port_parent
> of_graph_get_remote_port
> 
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> ---
>  drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> index 28c0620dfe0f..9484fdb60f68 100644
> --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -399,7 +399,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
>  
>  	/* Look up the DSI host.  It needs to probe before we do. */
>  	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	if (!endpoint)
> +		return -ENODEV;
> +
>  	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
> +	if (!dsi_host_node)
> +		return -ENODEV;
> +
If we return here we will leak endpoint - a of_node_put() is missing.
Use goto to rewind the allocations in the bottom of this function.

>  	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
>  	of_node_put(dsi_host_node);
>  	if (!host) {
> @@ -408,6 +414,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
>  	}
>  
>  	info.node = of_graph_get_remote_port(endpoint);
> +	if (!info.node)
> +		return -ENODEV;
Here we also leak endpoint, but not dsi_host_node as we already did a
put above.

> +
>  	of_node_put(endpoint);
>  
>  	ts->dsi = mipi_dsi_device_register_full(host, &info);

	Sam

[PATCH v2] drm/panel: check failure cases in the probe func

[Navid Emamdoost]

The following function calls may fail and return NULL, so the null check
is added.
of_graph_get_next_endpoint
of_graph_get_remote_port_parent
of_graph_get_remote_port

Update: Thanks to Sam Ravnborg, for suggession on the use of goto to avoid
leaking endpoint.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 .../gpu/drm/panel/panel-raspberrypi-touchscreen.c   | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 28c0620dfe0f..b5b14aa059ea 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -399,7 +399,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 
 	/* Look up the DSI host.  It needs to probe before we do. */
 	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return -ENODEV;
+
 	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		goto error;
+
 	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
 	of_node_put(dsi_host_node);
 	if (!host) {
@@ -408,6 +414,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 	}
 
 	info.node = of_graph_get_remote_port(endpoint);
+	if (!info.node)
+		goto error;
+
 	of_node_put(endpoint);
 
 	ts->dsi = mipi_dsi_device_register_full(host, &info);
@@ -428,6 +437,10 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 		return ret;
 
 	return 0;
+
+error:
+	of_node_put(endpoint);
+	return -ENODEV;
 }
 
 static int rpi_touchscreen_remove(struct i2c_client *i2c)
-- 
2.17.1

Re: [PATCH v2] drm/panel: check failure cases in the probe func

[Sam Ravnborg]

Hi Navid.

On Wed, Jul 24, 2019 at 02:55:34PM -0500, Navid Emamdoost wrote:
> The following function calls may fail and return NULL, so the null check
> is added.
> of_graph_get_next_endpoint
> of_graph_get_remote_port_parent
> of_graph_get_remote_port
> 
> Update: Thanks to Sam Ravnborg, for suggession on the use of goto to avoid
> leaking endpoint.
> 
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Applied and pushed to drm-misc-next.

	Sam