[PATCH v3] platform/x86: asus-wireless: Fail probe when there is no ACPI match

[Linmao Li]

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

asus_wireless_probe() returns success when acpi_match_acpi_device()
finds no match, leaving behind an input device that never reports
anything because the notify handler is not installed.  Worse, when the
driver is force-bound to a device without an ACPI companion, probe
still succeeds and stores a NULL companion pointer, which
asus_wireless_remove() later passes to acpi_dev_remove_notify_handler(),
leading to a NULL pointer dereference on unbind.

Return -ENODEV when the device does not match the ID table.  This also
covers the missing-companion case, because acpi_match_acpi_device()
rejects a NULL device.  Perform the check before allocating any driver
state, instead of after the input device has already been registered.

Fixes: f7e648027d7e ("platform/x86: asus-wireless: Convert ACPI driver to a platform one")
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Linmao Li <lilinmao@xxxxxxxxxx>
---
v3: Move the ACPI ID match before allocating driver state, instead of
    after the input device has already been registered (Ilpo).
v2: Fail probe when the ACPI ID match fails instead of adding a
    separate ACPI companion check at the top of probe (Rafael).

 drivers/platform/x86/asus-wireless.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/x86/asus-wireless.c b/drivers/platform/x86/asus-wireless.c
index 2b494bf3cba8..aab45f0442c5 100644
--- a/drivers/platform/x86/asus-wireless.c
+++ b/drivers/platform/x86/asus-wireless.c
@@ -132,6 +132,10 @@ static int asus_wireless_probe(struct platform_device *pdev)
 	const struct acpi_device_id *id;
 	int err;
 
+	id = acpi_match_acpi_device(device_ids, adev);
+	if (!id)
+		return -ENODEV;
+
 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
@@ -139,6 +143,7 @@ static int asus_wireless_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, data);
 
 	data->adev = adev;
+	data->hswc_params = (const struct hswc_params *)id->driver_data;
 
 	data->idev = devm_input_allocate_device(&pdev->dev);
 	if (!data->idev)
@@ -153,12 +158,6 @@ static int asus_wireless_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	id = acpi_match_acpi_device(device_ids, adev);
-	if (!id)
-		return 0;
-
-	data->hswc_params = (const struct hswc_params *)id->driver_data;
-
 	data->wq = create_singlethread_workqueue("asus_wireless_workqueue");
 	if (!data->wq)
 		return -ENOMEM;
-- 
2.25.1