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

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

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