From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Every platform driver can be forced to match a device that doesn't match
its list of device IDs because of device_match_driver_override(), so
platform drivers that rely on the existence of a device's ACPI companion
object need to verify its presence.

Accordingly, add a requisite ACPI_COMPANION() check against NULL to the
platform/x86 intel/rst driver.

Fixes: 163a68a31f74 ("platform/x86: intel/rst: Convert ACPI driver to a platform one")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/platform/x86/intel/rst.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel/rst.c b/drivers/platform/x86/intel/rst.c
index 4bd10927aad9..bb19f0d89305 100644
--- a/drivers/platform/x86/intel/rst.c
+++ b/drivers/platform/x86/intel/rst.c
@@ -102,9 +102,13 @@ static struct device_attribute irst_timeout_attr = {
 
 static int irst_probe(struct platform_device *pdev)
 {
-	struct acpi_device *acpi = ACPI_COMPANION(&pdev->dev);
+	struct acpi_device *acpi;
 	int error;
 
+	acpi = ACPI_COMPANION(&pdev->dev);
+	if (!acpi)
+		return -ENODEV;
+
 	error = device_create_file(&acpi->dev, &irst_timeout_attr);
 	if (unlikely(error))
 		return error;
-- 
2.51.0