[PATCH 1/7] USB: core: fix device node leak

[PATCH 1/7] USB: core: fix device node leak

[Johan Hovold]

Make sure to release any OF device-node reference taken when creating
the USB device.

Note that we currently do not hold a reference to the root hub
device-tree node (i.e. the parent controller node).

Fixes: 69bec7259853 ("USB: core: let USB device know device node")
Cc: stable <stable@vger.kernel.org>	# v4.6
Cc: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/core/usb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 28b053cacc90..62e1906bb2f3 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -416,6 +416,8 @@ static void usb_release_dev(struct device *dev)
 
 	usb_destroy_configuration(udev);
 	usb_release_bos_descriptor(udev);
+	if (udev->parent)
+		of_node_put(dev->of_node);
 	usb_put_hcd(hcd);
 	kfree(udev->product);
 	kfree(udev->manufacturer);
-- 
2.13.0

Re: [PATCH 1/7] USB: core: fix device node leak

[Tyrel Datwyler]

On 05/30/2017 09:25 AM, Johan Hovold wrote:
> Make sure to release any OF device-node reference taken when creating
> the USB device.
> 
> Note that we currently do not hold a reference to the root hub
> device-tree node (i.e. the parent controller node).
> 
> Fixes: 69bec7259853 ("USB: core: let USB device know device node")
> Cc: stable <stable@vger.kernel.org>	# v4.6
> Cc: Peter Chen <peter.chen@nxp.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/usb/core/usb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> index 28b053cacc90..62e1906bb2f3 100644
> --- a/drivers/usb/core/usb.c
> +++ b/drivers/usb/core/usb.c
> @@ -416,6 +416,8 @@ static void usb_release_dev(struct device *dev)
>  
>  	usb_destroy_configuration(udev);
>  	usb_release_bos_descriptor(udev);
> +	if (udev->parent)
> +		of_node_put(dev->of_node);

If I'm following the root hub doesn't hold an of_node reference, so does that guarantee
that dev->of_node is NULL for the root hub? If so of_node_put() is safely called with a
NULL reference, making the if(udev->parent) unnecessary, and further no need to remove it
in follow-up patch #5.

-Tyrel

>  	usb_put_hcd(hcd);
>  	kfree(udev->product);
>  	kfree(udev->manufacturer);
> 

Re: [PATCH 1/7] USB: core: fix device node leak

[Johan Hovold]

On Tue, May 30, 2017 at 03:55:56PM -0700, Tyrel Datwyler wrote:
> On 05/30/2017 09:25 AM, Johan Hovold wrote:
> > Make sure to release any OF device-node reference taken when creating
> > the USB device.
> > 
> > Note that we currently do not hold a reference to the root hub
> > device-tree node (i.e. the parent controller node).
> > 
> > Fixes: 69bec7259853 ("USB: core: let USB device know device node")
> > Cc: stable <stable@vger.kernel.org>	# v4.6
> > Cc: Peter Chen <peter.chen@nxp.com>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > ---
> >  drivers/usb/core/usb.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> > index 28b053cacc90..62e1906bb2f3 100644
> > --- a/drivers/usb/core/usb.c
> > +++ b/drivers/usb/core/usb.c
> > @@ -416,6 +416,8 @@ static void usb_release_dev(struct device *dev)
> >  
> >  	usb_destroy_configuration(udev);
> >  	usb_release_bos_descriptor(udev);
> > +	if (udev->parent)
> > +		of_node_put(dev->of_node);
> 
> If I'm following the root hub doesn't hold an of_node reference, so
> does that guarantee that dev->of_node is NULL for the root hub?

No, it may be non-NULL.

> If so of_node_put() is safely called with a NULL reference, making the
> if(udev->parent) unnecessary, and further no need to remove it in
> follow-up patch #5.

So this one is still needed.

Thanks,
Johan

Re: [PATCH 1/7] USB: core: fix device node leak

[Peter Chen]

On Tue, May 30, 2017 at 06:25:48PM +0200, Johan Hovold wrote:
> Make sure to release any OF device-node reference taken when creating
> the USB device.
> 
> Note that we currently do not hold a reference to the root hub
> device-tree node (i.e. the parent controller node).
> 
> Fixes: 69bec7259853 ("USB: core: let USB device know device node")
> Cc: stable <stable@vger.kernel.org>	# v4.6
> Cc: Peter Chen <peter.chen@nxp.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/usb/core/usb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> index 28b053cacc90..62e1906bb2f3 100644
> --- a/drivers/usb/core/usb.c
> +++ b/drivers/usb/core/usb.c
> @@ -416,6 +416,8 @@ static void usb_release_dev(struct device *dev)
>  
>  	usb_destroy_configuration(udev);
>  	usb_release_bos_descriptor(udev);
> +	if (udev->parent)
> +		of_node_put(dev->of_node);
>  	usb_put_hcd(hcd);
>  	kfree(udev->product);
>  	kfree(udev->manufacturer);

Acked-by: Peter Chen <peter.chen@nxp.com>

-- 

Best Regards,
Peter Chen

[PATCH 6/7] thermal: max77620: fix device-node reference imbalance

[Johan Hovold]

The thermal child device reuses the parent MFD-device device-tree node
when registering a thermal zone, but did not take a reference to the
node.

This leads to a reference imbalance, and potential use-after-free, when
the node reference is dropped by the platform-bus device destructor
(once for the child and later again for the parent).

Fix this by dropping any reference already held to a device-tree node
and getting a reference to the parent's node which will be balanced on
reprobe or on platform-device release, whichever comes first.

Note that simply clearing the of_node pointer on probe errors and on
driver unbind would not allow the use of device-managed resources as
specifically thermal_zone_of_sensor_unregister() claims that a valid
device-tree node pointer is needed during deregistration (even if it
currently does not seem to use it).

Fixes: ec4664b3fd6d ("thermal: max77620: Add thermal driver for reporting junction temp")
Cc: stable <stable@vger.kernel.org>     # 4.9
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/thermal/max77620_thermal.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/max77620_thermal.c b/drivers/thermal/max77620_thermal.c
index e9a1fe342760..71d35f3c9215 100644
--- a/drivers/thermal/max77620_thermal.c
+++ b/drivers/thermal/max77620_thermal.c
@@ -104,8 +104,6 @@ static int max77620_thermal_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	pdev->dev.of_node = pdev->dev.parent->of_node;
-
 	mtherm->dev = &pdev->dev;
 	mtherm->rmap = dev_get_regmap(pdev->dev.parent, NULL);
 	if (!mtherm->rmap) {
@@ -113,6 +111,14 @@ static int max77620_thermal_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	/*
+	 * Drop any current reference to a device-tree node and get a
+	 * reference to the parent's node which will be balanced on reprobe or
+	 * on platform-device release.
+	 */
+	of_node_put(pdev->dev.of_node);
+	pdev->dev.of_node = of_node_get(pdev->dev.parent->of_node);
+
 	mtherm->tz_device = devm_thermal_zone_of_sensor_register(&pdev->dev, 0,
 				mtherm, &max77620_thermal_ops);
 	if (IS_ERR(mtherm->tz_device)) {
-- 
2.13.0

Re: [PATCH 6/7] thermal: max77620: fix device-node reference imbalance

[Tyrel Datwyler]

On 05/30/2017 09:25 AM, Johan Hovold wrote:
> The thermal child device reuses the parent MFD-device device-tree node
> when registering a thermal zone, but did not take a reference to the
> node.
> 
> This leads to a reference imbalance, and potential use-after-free, when
> the node reference is dropped by the platform-bus device destructor
> (once for the child and later again for the parent).
> 
> Fix this by dropping any reference already held to a device-tree node
> and getting a reference to the parent's node which will be balanced on
> reprobe or on platform-device release, whichever comes first.
> 
> Note that simply clearing the of_node pointer on probe errors and on
> driver unbind would not allow the use of device-managed resources as
> specifically thermal_zone_of_sensor_unregister() claims that a valid
> device-tree node pointer is needed during deregistration (even if it
> currently does not seem to use it).
> 
> Fixes: ec4664b3fd6d ("thermal: max77620: Add thermal driver for reporting junction temp")
> Cc: stable <stable@vger.kernel.org>     # 4.9
> Cc: Laxman Dewangan <ldewangan@nvidia.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/thermal/max77620_thermal.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/thermal/max77620_thermal.c b/drivers/thermal/max77620_thermal.c
> index e9a1fe342760..71d35f3c9215 100644
> --- a/drivers/thermal/max77620_thermal.c
> +++ b/drivers/thermal/max77620_thermal.c
> @@ -104,8 +104,6 @@ static int max77620_thermal_probe(struct platform_device *pdev)
>  		return -EINVAL;
>  	}
>  
> -	pdev->dev.of_node = pdev->dev.parent->of_node;
> -
>  	mtherm->dev = &pdev->dev;
>  	mtherm->rmap = dev_get_regmap(pdev->dev.parent, NULL);
>  	if (!mtherm->rmap) {
> @@ -113,6 +111,14 @@ static int max77620_thermal_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  	}
>  
> +	/*
> +	 * Drop any current reference to a device-tree node and get a
> +	 * reference to the parent's node which will be balanced on reprobe or
> +	 * on platform-device release.
> +	 */
> +	of_node_put(pdev->dev.of_node);
> +	pdev->dev.of_node = of_node_get(pdev->dev.parent->of_node);
> +

This seems like needless churn. Can't this just be squashed into patch #7?

-Tyrel

>  	mtherm->tz_device = devm_thermal_zone_of_sensor_register(&pdev->dev, 0,
>  				mtherm, &max77620_thermal_ops);
>  	if (IS_ERR(mtherm->tz_device)) {
> 

Re: [PATCH 6/7] thermal: max77620: fix device-node reference imbalance

[Johan Hovold]

On Tue, May 30, 2017 at 03:59:10PM -0700, Tyrel Datwyler wrote:
> On 05/30/2017 09:25 AM, Johan Hovold wrote:
> > The thermal child device reuses the parent MFD-device device-tree node
> > when registering a thermal zone, but did not take a reference to the
> > node.
> > 
> > This leads to a reference imbalance, and potential use-after-free, when
> > the node reference is dropped by the platform-bus device destructor
> > (once for the child and later again for the parent).
> > 
> > Fix this by dropping any reference already held to a device-tree node
> > and getting a reference to the parent's node which will be balanced on
> > reprobe or on platform-device release, whichever comes first.
> > 
> > Note that simply clearing the of_node pointer on probe errors and on
> > driver unbind would not allow the use of device-managed resources as
> > specifically thermal_zone_of_sensor_unregister() claims that a valid
> > device-tree node pointer is needed during deregistration (even if it
> > currently does not seem to use it).
> > 
> > Fixes: ec4664b3fd6d ("thermal: max77620: Add thermal driver for reporting junction temp")
> > Cc: stable <stable@vger.kernel.org>     # 4.9
> > Cc: Laxman Dewangan <ldewangan@nvidia.com>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > ---
> >  drivers/thermal/max77620_thermal.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/thermal/max77620_thermal.c b/drivers/thermal/max77620_thermal.c
> > index e9a1fe342760..71d35f3c9215 100644
> > --- a/drivers/thermal/max77620_thermal.c
> > +++ b/drivers/thermal/max77620_thermal.c
> > @@ -104,8 +104,6 @@ static int max77620_thermal_probe(struct platform_device *pdev)
> >  		return -EINVAL;
> >  	}
> >  
> > -	pdev->dev.of_node = pdev->dev.parent->of_node;
> > -
> >  	mtherm->dev = &pdev->dev;
> >  	mtherm->rmap = dev_get_regmap(pdev->dev.parent, NULL);
> >  	if (!mtherm->rmap) {
> > @@ -113,6 +111,14 @@ static int max77620_thermal_probe(struct platform_device *pdev)
> >  		return -ENODEV;
> >  	}
> >  
> > +	/*
> > +	 * Drop any current reference to a device-tree node and get a
> > +	 * reference to the parent's node which will be balanced on reprobe or
> > +	 * on platform-device release.
> > +	 */
> > +	of_node_put(pdev->dev.of_node);
> > +	pdev->dev.of_node = of_node_get(pdev->dev.parent->of_node);
> > +
> 
> This seems like needless churn. Can't this just be squashed into patch
> #7?

As I just replied to Eduardo, I'm fixing two separate issues here of
which this one might qualify for stable while the other (7/7) does not.

Thanks,
Johan