[PATCH v2] net: rfkill: gpio: Fix crash due to dereferencering uninitialized pointer

[PATCH v2] net: rfkill: gpio: Fix crash due to dereferencering uninitialized pointer

[Hans de Goede]

Since commit 7d5e9737efda ("net: rfkill: gpio: get the name and type from
device property") rfkill_find_type() gets called with the possibly
uninitialized "const char *type_name;" local variable.

On x86 systems when rfkill-gpio binds to a "BCM4752" or "LNV4752"
acpi_device, the rfkill->type is set based on the ACPI acpi_device_id:

        rfkill->type = (unsigned)id->driver_data;

and there is no "type" property so device_property_read_string() will fail
and leave type_name uninitialized, leading to a potential crash.

rfkill_find_type() does accept a NULL pointer, fix the potential crash
by initializing type_name to NULL.

Note likely sofar this has not been caught because:

1. Not many x86 machines actually have a "BCM4752"/"LNV4752" acpi_device
2. The stack happened to contain NULL where type_name is stored

Fixes: 7d5e9737efda ("net: rfkill: gpio: get the name and type from device property")
Cc: stable@vger.kernel.org
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hans de Goede <hansg@kernel.org>
---
Changes in v2:
- Fix typo in stable email address
---
 net/rfkill/rfkill-gpio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/rfkill/rfkill-gpio.c b/net/rfkill/rfkill-gpio.c
index 41e657e97761..cf2dcec6ce5a 100644
--- a/net/rfkill/rfkill-gpio.c
+++ b/net/rfkill/rfkill-gpio.c
@@ -94,10 +94,10 @@ static const struct dmi_system_id rfkill_gpio_deny_table[] = {
 static int rfkill_gpio_probe(struct platform_device *pdev)
 {
 	struct rfkill_gpio_data *rfkill;
-	struct gpio_desc *gpio;
+	const char *type_name = NULL;
 	const char *name_property;
 	const char *type_property;
-	const char *type_name;
+	struct gpio_desc *gpio;
 	int ret;
 
 	if (dmi_check_system(rfkill_gpio_deny_table))
-- 
2.51.0

Re: [PATCH v2] net: rfkill: gpio: Fix crash due to dereferencering uninitialized pointer

[Heikki Krogerus]

On Sat, Sep 13, 2025 at 01:35:15PM +0200, Hans de Goede wrote:
> Since commit 7d5e9737efda ("net: rfkill: gpio: get the name and type from
> device property") rfkill_find_type() gets called with the possibly
> uninitialized "const char *type_name;" local variable.
> 
> On x86 systems when rfkill-gpio binds to a "BCM4752" or "LNV4752"
> acpi_device, the rfkill->type is set based on the ACPI acpi_device_id:
> 
>         rfkill->type = (unsigned)id->driver_data;
> 
> and there is no "type" property so device_property_read_string() will fail
> and leave type_name uninitialized, leading to a potential crash.
> 
> rfkill_find_type() does accept a NULL pointer, fix the potential crash
> by initializing type_name to NULL.
> 
> Note likely sofar this has not been caught because:
> 
> 1. Not many x86 machines actually have a "BCM4752"/"LNV4752" acpi_device
> 2. The stack happened to contain NULL where type_name is stored
> 
> Fixes: 7d5e9737efda ("net: rfkill: gpio: get the name and type from device property")
> Cc: stable@vger.kernel.org
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Signed-off-by: Hans de Goede <hansg@kernel.org>

FWIW:

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Changes in v2:
> - Fix typo in stable email address
> ---
>  net/rfkill/rfkill-gpio.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/rfkill/rfkill-gpio.c b/net/rfkill/rfkill-gpio.c
> index 41e657e97761..cf2dcec6ce5a 100644
> --- a/net/rfkill/rfkill-gpio.c
> +++ b/net/rfkill/rfkill-gpio.c
> @@ -94,10 +94,10 @@ static const struct dmi_system_id rfkill_gpio_deny_table[] = {
>  static int rfkill_gpio_probe(struct platform_device *pdev)
>  {
>  	struct rfkill_gpio_data *rfkill;
> -	struct gpio_desc *gpio;
> +	const char *type_name = NULL;
>  	const char *name_property;
>  	const char *type_property;
> -	const char *type_name;
> +	struct gpio_desc *gpio;
>  	int ret;
>  
>  	if (dmi_check_system(rfkill_gpio_deny_table))
> -- 
> 2.51.0

-- 
heikki