[PATCH] regulator: fixed: reject incompatible platform devices

[Chandradhar Kumar]

The fixed regulator driver expects non-DT platform devices to provide
their configuration through platform_data as a struct fixed_voltage_config.

An explicitly bound driver can bypass the normal platform device/driver
matching and attach the fixed regulator driver to an unrelated platform
device. This causes the driver's platform_data to be interpreted as a
struct fixed_voltage_config even though it contains data for a different
device.

Reject non-DT platform devices whose name does not match the fixed
regulator driver before accessing their platform data.

Fixes: 4b74ff651249 ("regulator: add support for fixed regulators.")
Reported-by: syzbot+bfc9e55cf4f98183c636@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzbot.org/bug?extid=bfc9e55cf4f98183c636
Signed-off-by: Chandradhar Kumar <chandradhar.2003@xxxxxxxxx>
---
 drivers/regulator/fixed.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/regulator/fixed.c b/drivers/regulator/fixed.c
index 417d282dd4ed..faa82f30eb1f 100644
--- a/drivers/regulator/fixed.c
+++ b/drivers/regulator/fixed.c
@@ -28,6 +28,7 @@
 #include <linux/regulator/of_regulator.h>
 #include <linux/regulator/machine.h>
 #include <linux/clk.h>
+#include <linux/string.h>
 
 struct fixed_voltage_data {
 	struct regulator_desc desc;
@@ -225,6 +226,9 @@ static int reg_fixed_voltage_probe(struct platform_device *pdev)
 	enum gpiod_flags gflags;
 	int ret;
 
+	if (!pdev->dev.of_node && strcmp(pdev->name, "reg-fixed-voltage"))
+		return -ENODEV;
+
 	drvdata = devm_kzalloc(&pdev->dev, sizeof(struct fixed_voltage_data),
 			       GFP_KERNEL);
 	if (!drvdata)
-- 
2.55.0