[PATCH 1/2] platform/chrome: cros_ec_uart: check ACPI companion before use

[Jiale Yao <yaojiale02@163.com>]

cros_ec_uart_acpi_probe() passes the ACPI companion to resource helpers
without checking it. A serdev force-bound without an ACPI companion can
therefore cause a NULL pointer dereference during probe.

Reject devices without an ACPI companion before parsing their resources.

Fixes: 04a8bdd135cc ("platform/chrome: cros_ec_uart: Add transport layer")
Cc: stable@vger.kernel.org
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/platform/chrome/cros_ec_uart.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
index d5b37414ff12..779aabd16674 100644
--- a/drivers/platform/chrome/cros_ec_uart.c
+++ b/drivers/platform/chrome/cros_ec_uart.c
@@ -223,9 +223,13 @@ static int cros_ec_uart_resource(struct acpi_resource *ares, void *data)
 
 static int cros_ec_uart_acpi_probe(struct cros_ec_uart *ec_uart)
 {
-	int ret;
+	struct acpi_device *adev;
 	LIST_HEAD(resources);
-	struct acpi_device *adev = ACPI_COMPANION(&ec_uart->serdev->dev);
+	int ret;
+
+	adev = ACPI_COMPANION(&ec_uart->serdev->dev);
+	if (!adev)
+		return -ENODEV;
 
 	ret = acpi_dev_get_resources(adev, &resources, cros_ec_uart_resource, ec_uart);
 	if (ret < 0)
-- 
2.34.1