[PATCH master 1/2] regulator: handle regulator_get_voltage(NULL) gracefully

[PATCH master 1/2] regulator: handle regulator_get_voltage(NULL) gracefully

[Ahmad Fatoum]

Unlike recent versions of Linux, barebox represents the dummy regulator
as a NULL pointer and regulator API is supposed to anticipate operation
on a NULL pointer. When regulator_get_voltage was ported from Linux,
this was not taken into consideration, which leads to
regulator_get_voltage(NULL) crashing with a NULL pointer dereference.

Fix this by returning -EINVAL for dummy regulators. This aligns us with
how Linux would behave in this situation.

Fixes: 6ee83ce08b24 ("regulator: add regulator_get_voltage() to API")
Reported-by: Johannes Zink <j.zink@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/regulator/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 1fb344656f38..472b26f3a0ac 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -574,9 +574,14 @@ EXPORT_SYMBOL_GPL(regulator_bulk_free);
 
 int regulator_get_voltage(struct regulator *regulator)
 {
-	struct regulator_dev *rdev = regulator->ri->rdev;
+	struct regulator_dev *rdev;
 	int sel, ret;
 
+	if (!regulator)
+		return -EINVAL;
+
+	rdev = regulator->ri->rdev;
+
 	if (rdev->desc->ops->get_voltage_sel) {
 		sel = rdev->desc->ops->get_voltage_sel(rdev);
 		if (sel < 0)
-- 
2.30.2

[PATCH master 2/2] common: don't fixup empty serial/machine_compatible strings

[Ahmad Fatoum]

There is no point in fixing up an empty string into the kernel device
tree, yet this can happen when globalvar_add_simple_string() is called
for the variable at least once as the function replaces NULL with an
allocated empty string. globalvar_add_simple_string() was called
unconditionally for of.kernel.add_machine_compatible, which in turn
led to always fixing up an empty string as the top-most compatible.

Resolve this by having barebox_get_(of_machine_compatible|serial_number)
return NULL for the empty string as well.

Fixes: 81dd24a0946c ("of: add generic of_prepend_machine_compatible()")
Fixes: f6756e9ce6f2 ("common: add $global.serial_number with device tree fixup")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 common/misc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/misc.c b/common/misc.c
index 0f6de3e9e5ef..e0e32f47c59d 100644
--- a/common/misc.c
+++ b/common/misc.c
@@ -191,6 +191,8 @@ void barebox_set_serial_number(const char *__serial_number)
 
 const char *barebox_get_serial_number(void)
 {
+	if (!serial_number || *serial_number == '\0')
+		return NULL;
 	return serial_number;
 }
 
@@ -204,6 +206,8 @@ void barebox_set_of_machine_compatible(const char *__compatible)
 
 const char *barebox_get_of_machine_compatible(void)
 {
+	if (!of_machine_compatible || *of_machine_compatible == '\0')
+		return NULL;
 	return of_machine_compatible;
 }
 
-- 
2.30.2

Re: [PATCH master 1/2] regulator: handle regulator_get_voltage(NULL) gracefully

[Sascha Hauer]

On Mon, Jul 18, 2022 at 01:48:23PM +0200, Ahmad Fatoum wrote:
> Unlike recent versions of Linux, barebox represents the dummy regulator
> as a NULL pointer and regulator API is supposed to anticipate operation
> on a NULL pointer. When regulator_get_voltage was ported from Linux,
> this was not taken into consideration, which leads to
> regulator_get_voltage(NULL) crashing with a NULL pointer dereference.
> 
> Fix this by returning -EINVAL for dummy regulators. This aligns us with
> how Linux would behave in this situation.
> 
> Fixes: 6ee83ce08b24 ("regulator: add regulator_get_voltage() to API")
> Reported-by: Johannes Zink <j.zink@pengutronix.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/regulator/core.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Applied, thanks

Sascha

> 
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 1fb344656f38..472b26f3a0ac 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -574,9 +574,14 @@ EXPORT_SYMBOL_GPL(regulator_bulk_free);
>  
>  int regulator_get_voltage(struct regulator *regulator)
>  {
> -	struct regulator_dev *rdev = regulator->ri->rdev;
> +	struct regulator_dev *rdev;
>  	int sel, ret;
>  
> +	if (!regulator)
> +		return -EINVAL;
> +
> +	rdev = regulator->ri->rdev;
> +
>  	if (rdev->desc->ops->get_voltage_sel) {
>  		sel = rdev->desc->ops->get_voltage_sel(rdev);
>  		if (sel < 0)
> -- 
> 2.30.2
> 
> 
> 

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