[PATCH v1 1/3] serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

[PATCH v1 1/3] serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

[Andy Shevchenko]

It's possible that during ->exit() the private_data is NULL,
for instance when there was no GPIO device instantiated.
Due to this we may not dereference it. Add a respective check.

Note, for now ->exit() only makes sense when GPIO device
was instantiated, that's why we may use the check for entire
function.

Fixes: 81171e7d31a6 ("serial: 8250_exar: Constify the software nodes")
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/tty/serial/8250/8250_exar.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 2f49c580139b..bd4e9f6ac29c 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -553,7 +553,11 @@ static void pci_xr17v35x_exit(struct pci_dev *pcidev)
 {
 	struct exar8250 *priv = pci_get_drvdata(pcidev);
 	struct uart_8250_port *port = serial8250_get_port(priv->line[0]);
-	struct platform_device *pdev = port->port.private_data;
+	struct platform_device *pdev;
+
+	pdev = port->port.private_data;
+	if (!pdev)
+		return;
 
 	device_remove_software_node(&pdev->dev);
 	platform_device_unregister(pdev);
-- 
2.30.2

[PATCH v1 2/3] serial: 8250_exar: Extract exar_get_platform() helper

[Andy Shevchenko]

We would like to use DMI matching in other functions as well.
Hence, extract it as exar_get_platform() helper function.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/tty/serial/8250/8250_exar.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index bd4e9f6ac29c..3ffeedc29c83 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -501,23 +501,27 @@ static const struct dmi_system_id exar_platforms[] = {
 	{}
 };
 
+static const struct exar8250_platform *exar_get_platform(void)
+{
+	const struct dmi_system_id *dmi_match;
+
+	dmi_match = dmi_first_match(exar_platforms);
+	if (dmi_match)
+		return dmi_match->driver_data;
+
+	return &exar8250_default_platform;
+}
+
 static int
 pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
 		   struct uart_8250_port *port, int idx)
 {
-	const struct exar8250_platform *platform;
-	const struct dmi_system_id *dmi_match;
+	const struct exar8250_platform *platform = exar_get_platform();
 	unsigned int offset = idx * 0x400;
 	unsigned int baud = 7812500;
 	u8 __iomem *p;
 	int ret;
 
-	dmi_match = dmi_first_match(exar_platforms);
-	if (dmi_match)
-		platform = dmi_match->driver_data;
-	else
-		platform = &exar8250_default_platform;
-
 	port->port.uartclk = baud * 16;
 	port->port.rs485_config = platform->rs485_config;
 
-- 
2.30.2

[PATCH v1 3/3] serial: 8250_exar: Add ->unregister_gpio() callback

[Andy Shevchenko]

For the sake of reducing layering violation add ->unregister_gpio()
callback and use it in the ->exit() one.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/tty/serial/8250/8250_exar.c | 36 ++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 3ffeedc29c83..d502240bbcf2 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -114,6 +114,7 @@ struct exar8250;
 struct exar8250_platform {
 	int (*rs485_config)(struct uart_port *, struct serial_rs485 *);
 	int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
+	void (*unregister_gpio)(struct uart_8250_port *);
 };
 
 /**
@@ -352,9 +353,8 @@ static void setup_gpio(struct pci_dev *pcidev, u8 __iomem *p)
 	writeb(0x00, p + UART_EXAR_MPIOOD_15_8);
 }
 
-static void *
-__xr17v35x_register_gpio(struct pci_dev *pcidev,
-			 const struct software_node *node)
+static struct platform_device *__xr17v35x_register_gpio(struct pci_dev *pcidev,
+							const struct software_node *node)
 {
 	struct platform_device *pdev;
 
@@ -374,6 +374,12 @@ __xr17v35x_register_gpio(struct pci_dev *pcidev,
 	return pdev;
 }
 
+static void __xr17v35x_unregister_gpio(struct platform_device *pdev)
+{
+	device_remove_software_node(&pdev->dev);
+	platform_device_unregister(pdev);
+}
+
 static const struct property_entry exar_gpio_properties[] = {
 	PROPERTY_ENTRY_U32("exar,first-pin", 0),
 	PROPERTY_ENTRY_U32("ngpios", 16),
@@ -384,8 +390,7 @@ static const struct software_node exar_gpio_node = {
 	.properties = exar_gpio_properties,
 };
 
-static int xr17v35x_register_gpio(struct pci_dev *pcidev,
-				  struct uart_8250_port *port)
+static int xr17v35x_register_gpio(struct pci_dev *pcidev, struct uart_8250_port *port)
 {
 	if (pcidev->vendor == PCI_VENDOR_ID_EXAR)
 		port->port.private_data =
@@ -394,6 +399,15 @@ static int xr17v35x_register_gpio(struct pci_dev *pcidev,
 	return 0;
 }
 
+static void xr17v35x_unregister_gpio(struct uart_8250_port *port)
+{
+	if (!port->port.private_data)
+		return;
+
+	__xr17v35x_unregister_gpio(port->port.private_data);
+	port->port.private_data = NULL;
+}
+
 static int generic_rs485_config(struct uart_port *port,
 				struct serial_rs485 *rs485)
 {
@@ -419,6 +433,7 @@ static int generic_rs485_config(struct uart_port *port,
 
 static const struct exar8250_platform exar8250_default_platform = {
 	.register_gpio = xr17v35x_register_gpio,
+	.unregister_gpio = xr17v35x_unregister_gpio,
 	.rs485_config = generic_rs485_config,
 };
 
@@ -484,6 +499,7 @@ static int iot2040_register_gpio(struct pci_dev *pcidev,
 static const struct exar8250_platform iot2040_platform = {
 	.rs485_config = iot2040_rs485_config,
 	.register_gpio = iot2040_register_gpio,
+	.unregister_gpio = xr17v35x_unregister_gpio,
 };
 
 /*
@@ -555,17 +571,11 @@ pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
 
 static void pci_xr17v35x_exit(struct pci_dev *pcidev)
 {
+	const struct exar8250_platform *platform = exar_get_platform();
 	struct exar8250 *priv = pci_get_drvdata(pcidev);
 	struct uart_8250_port *port = serial8250_get_port(priv->line[0]);
-	struct platform_device *pdev;
 
-	pdev = port->port.private_data;
-	if (!pdev)
-		return;
-
-	device_remove_software_node(&pdev->dev);
-	platform_device_unregister(pdev);
-	port->port.private_data = NULL;
+	platform->unregister_gpio(port);
 }
 
 static inline void exar_misc_clear(struct exar8250 *priv)
-- 
2.30.2

Re: [PATCH v1 1/3] serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

[Maxim Levitsky]

On Tue, 2021-06-08 at 17:42 +0300, Andy Shevchenko wrote:
> It's possible that during ->exit() the private_data is NULL,
> for instance when there was no GPIO device instantiated.
> Due to this we may not dereference it. Add a respective check.
> 
> Note, for now ->exit() only makes sense when GPIO device
> was instantiated, that's why we may use the check for entire
> function.
> 
> Fixes: 81171e7d31a6 ("serial: 8250_exar: Constify the software nodes")
> Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_exar.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index 2f49c580139b..bd4e9f6ac29c 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -553,7 +553,11 @@ static void pci_xr17v35x_exit(struct pci_dev *pcidev)
>  {
>  	struct exar8250 *priv = pci_get_drvdata(pcidev);
>  	struct uart_8250_port *port = serial8250_get_port(priv->line[0]);
> -	struct platform_device *pdev = port->port.private_data;
> +	struct platform_device *pdev;
> +
> +	pdev = port->port.private_data;
> +	if (!pdev)
> +		return;
>  
>  	device_remove_software_node(&pdev->dev);
>  	platform_device_unregister(pdev);

Hi!

I just tested this patch and it does work!
Thanks a lot for fixing this that fast!

Tested-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky

Re: [PATCH v1 2/3] serial: 8250_exar: Extract exar_get_platform() helper

[Greg Kroah-Hartman]

On Tue, Jun 08, 2021 at 05:42:38PM +0300, Andy Shevchenko wrote:
> We would like to use DMI matching in other functions as well.
> Hence, extract it as exar_get_platform() helper function.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_exar.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index bd4e9f6ac29c..3ffeedc29c83 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -501,23 +501,27 @@ static const struct dmi_system_id exar_platforms[] = {
>  	{}
>  };
>  
> +static const struct exar8250_platform *exar_get_platform(void)
> +{
> +	const struct dmi_system_id *dmi_match;
> +
> +	dmi_match = dmi_first_match(exar_platforms);
> +	if (dmi_match)
> +		return dmi_match->driver_data;
> +
> +	return &exar8250_default_platform;
> +}
> +
>  static int
>  pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
>  		   struct uart_8250_port *port, int idx)
>  {
> -	const struct exar8250_platform *platform;
> -	const struct dmi_system_id *dmi_match;
> +	const struct exar8250_platform *platform = exar_get_platform();
>  	unsigned int offset = idx * 0x400;
>  	unsigned int baud = 7812500;
>  	u8 __iomem *p;
>  	int ret;
>  
> -	dmi_match = dmi_first_match(exar_platforms);
> -	if (dmi_match)
> -		platform = dmi_match->driver_data;
> -	else
> -		platform = &exar8250_default_platform;
> -
>  	port->port.uartclk = baud * 16;
>  	port->port.rs485_config = platform->rs485_config;
>  
> -- 
> 2.30.2
> 

Do not mix "fixes with features" in a single series, as I now have to
pick it apart and apply it to different branches by hand :(

Please do different series for the two different things if at all
possible.

thanks,

greg k-h

Re: [PATCH v1 3/3] serial: 8250_exar: Add ->unregister_gpio() callback

[Greg Kroah-Hartman]

On Tue, Jun 08, 2021 at 05:42:39PM +0300, Andy Shevchenko wrote:
> For the sake of reducing layering violation add ->unregister_gpio()
> callback and use it in the ->exit() one.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_exar.c | 36 ++++++++++++++++++-----------
>  1 file changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index 3ffeedc29c83..d502240bbcf2 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -114,6 +114,7 @@ struct exar8250;
>  struct exar8250_platform {
>  	int (*rs485_config)(struct uart_port *, struct serial_rs485 *);
>  	int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
> +	void (*unregister_gpio)(struct uart_8250_port *);
>  };
>  
>  /**
> @@ -352,9 +353,8 @@ static void setup_gpio(struct pci_dev *pcidev, u8 __iomem *p)
>  	writeb(0x00, p + UART_EXAR_MPIOOD_15_8);
>  }
>  
> -static void *
> -__xr17v35x_register_gpio(struct pci_dev *pcidev,
> -			 const struct software_node *node)
> +static struct platform_device *__xr17v35x_register_gpio(struct pci_dev *pcidev,
> +							const struct software_node *node)
>  {
>  	struct platform_device *pdev;
>  
> @@ -374,6 +374,12 @@ __xr17v35x_register_gpio(struct pci_dev *pcidev,
>  	return pdev;
>  }
>  
> +static void __xr17v35x_unregister_gpio(struct platform_device *pdev)
> +{
> +	device_remove_software_node(&pdev->dev);
> +	platform_device_unregister(pdev);
> +}
> +
>  static const struct property_entry exar_gpio_properties[] = {
>  	PROPERTY_ENTRY_U32("exar,first-pin", 0),
>  	PROPERTY_ENTRY_U32("ngpios", 16),
> @@ -384,8 +390,7 @@ static const struct software_node exar_gpio_node = {
>  	.properties = exar_gpio_properties,
>  };
>  
> -static int xr17v35x_register_gpio(struct pci_dev *pcidev,
> -				  struct uart_8250_port *port)
> +static int xr17v35x_register_gpio(struct pci_dev *pcidev, struct uart_8250_port *port)
>  {
>  	if (pcidev->vendor == PCI_VENDOR_ID_EXAR)
>  		port->port.private_data =
> @@ -394,6 +399,15 @@ static int xr17v35x_register_gpio(struct pci_dev *pcidev,
>  	return 0;
>  }
>  
> +static void xr17v35x_unregister_gpio(struct uart_8250_port *port)
> +{
> +	if (!port->port.private_data)
> +		return;
> +
> +	__xr17v35x_unregister_gpio(port->port.private_data);
> +	port->port.private_data = NULL;
> +}
> +
>  static int generic_rs485_config(struct uart_port *port,
>  				struct serial_rs485 *rs485)
>  {
> @@ -419,6 +433,7 @@ static int generic_rs485_config(struct uart_port *port,
>  
>  static const struct exar8250_platform exar8250_default_platform = {
>  	.register_gpio = xr17v35x_register_gpio,
> +	.unregister_gpio = xr17v35x_unregister_gpio,
>  	.rs485_config = generic_rs485_config,
>  };
>  
> @@ -484,6 +499,7 @@ static int iot2040_register_gpio(struct pci_dev *pcidev,
>  static const struct exar8250_platform iot2040_platform = {
>  	.rs485_config = iot2040_rs485_config,
>  	.register_gpio = iot2040_register_gpio,
> +	.unregister_gpio = xr17v35x_unregister_gpio,
>  };
>  
>  /*
> @@ -555,17 +571,11 @@ pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
>  
>  static void pci_xr17v35x_exit(struct pci_dev *pcidev)
>  {
> +	const struct exar8250_platform *platform = exar_get_platform();
>  	struct exar8250 *priv = pci_get_drvdata(pcidev);
>  	struct uart_8250_port *port = serial8250_get_port(priv->line[0]);
> -	struct platform_device *pdev;
>  
> -	pdev = port->port.private_data;
> -	if (!pdev)
> -		return;
> -
> -	device_remove_software_node(&pdev->dev);
> -	platform_device_unregister(pdev);
> -	port->port.private_data = NULL;
> +	platform->unregister_gpio(port);
>  }
>  
>  static inline void exar_misc_clear(struct exar8250 *priv)
> -- 
> 2.30.2
> 

This patch doesn't apply to my tty-next branch, so I've dropped it :(

greg k-h

Re: [PATCH v1 2/3] serial: 8250_exar: Extract exar_get_platform() helper

[Andy Shevchenko]

On Wed, Jun 09, 2021 at 02:41:38PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Jun 08, 2021 at 05:42:38PM +0300, Andy Shevchenko wrote:
> > We would like to use DMI matching in other functions as well.
> > Hence, extract it as exar_get_platform() helper function.

> Do not mix "fixes with features" in a single series, as I now have to
> pick it apart and apply it to different branches by hand :(
> 
> Please do different series for the two different things if at all
> possible.

I see. Thank  you for pointing out, I will keep in mind for the future submissions.

-- 
With Best Regards,
Andy Shevchenko