linux-kernel - [PATCH v2] platform/x86: wmi: Make input buffer madatory when evaulating methods

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Message-Id: <20240212185016.5494-1-W_Armin@gmx.de>
Date: Mon, 12 Feb 2024 19:50:16 +0100
From: Armin Wolf <W_Armin@....de>
To: hdegoede@...hat.com,
	ilpo.jarvinen@...ux.intel.com
Cc: sathyanarayanan.kuppuswamy@...ux.intel.com,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] platform/x86: wmi: Make input buffer madatory when evaulating methods

The ACPI-WMI specification declares in the section "ACPI Control Method
Naming Conventions and Functionality for Windows 2000 Instrumentation"
that a WMxx control method takes 3 arguments: instance, method id and
argument buffer.
This is also the case even when the underlying WMI method does not
have any input arguments.

So if a WMI driver evaluates a WMI method without passing an input
buffer, ACPICA will log a warning complaining that the third argument
is missing.

Prevent this by checking that a input buffer was passed, and return
an error if this was not the case.

Tested on a Asus PRIME B650-Plus.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@....de>
---
Changes since v1:
- add section reference
- add Reviewed-by
---
 drivers/platform/x86/wmi.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 63906fdd0abf..f9e23d491dd9 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -296,7 +296,7 @@ EXPORT_SYMBOL_GPL(wmidev_instance_count);
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
  * @instance: Instance index
  * @method_id: Method ID to call
- * @in: Buffer containing input for the method call
+ * @in: Mandatory buffer containing input for the method call
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method, the caller must free @out.
@@ -326,7 +326,7 @@ EXPORT_SYMBOL_GPL(wmi_evaluate_method);
  * @wdev: A wmi bus device from a driver
  * @instance: Instance index
  * @method_id: Method ID to call
- * @in: Buffer containing input for the method call
+ * @in: Mandatory buffer containing input for the method call
  * @out: Empty buffer to return the method results
  *
  * Call an ACPI-WMI method, the caller must free @out.
@@ -347,26 +347,25 @@ acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 met
 	block = &wblock->gblock;
 	handle = wblock->acpi_device->handle;

+	if (!in)
+		return AE_BAD_DATA;
+
 	if (!(block->flags & ACPI_WMI_METHOD))
 		return AE_BAD_DATA;

 	if (block->instance_count <= instance)
 		return AE_BAD_PARAMETER;

-	input.count = 2;
+	input.count = 3;
 	input.pointer = params;
+
 	params[0].type = ACPI_TYPE_INTEGER;
 	params[0].integer.value = instance;
 	params[1].type = ACPI_TYPE_INTEGER;
 	params[1].integer.value = method_id;
-
-	if (in) {
-		input.count = 3;
-
-		params[2].type = get_param_acpi_type(wblock);
-		params[2].buffer.length = in->length;
-		params[2].buffer.pointer = in->pointer;
-	}
+	params[2].type = get_param_acpi_type(wblock);
+	params[2].buffer.length = in->length;
+	params[2].buffer.pointer = in->pointer;

 	get_acpi_method_name(wblock, 'M', method);

--
2.39.2