linux-kernel - Re: [PATCH 05/10] platform/x86: alienware-wmi-wmax: Improve platform profile probe

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Message-ID: <f8a5b533-15a6-46ac-8593-debc5e1cd151@gmx.de>
Date: Sun, 16 Feb 2025 06:57:17 +0100
From: Armin Wolf <W_Armin@....de>
To: Kurt Borja <kuurtb@...il.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: platform-driver-x86@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
 Dell.Client.Kernel@...l.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/10] platform/x86: alienware-wmi-wmax: Improve platform
 profile probe

Am 08.02.25 um 06:16 schrieb Kurt Borja:

> Get and store the AWCC system description in alienware_awcc_setup()
> instead of awcc_platform_profile_probe() and add a check for integer
> overflows to avoid misbehaviors.
>
> Signed-off-by: Kurt Borja <kuurtb@...il.com>
> ---
>   .../platform/x86/dell/alienware-wmi-wmax.c    | 56 ++++++++++++++-----
>   1 file changed, 43 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/platform/x86/dell/alienware-wmi-wmax.c b/drivers/platform/x86/dell/alienware-wmi-wmax.c
> index 4a8335d90b5d..e8fe16da036a 100644
> --- a/drivers/platform/x86/dell/alienware-wmi-wmax.c
> +++ b/drivers/platform/x86/dell/alienware-wmi-wmax.c
> @@ -12,6 +12,7 @@
>   #include <linux/bits.h>
>   #include <linux/dmi.h>
>   #include <linux/moduleparam.h>
> +#include <linux/overflow.h>
>   #include <linux/platform_profile.h>
>   #include <linux/wmi.h>
>   #include "alienware-wmi.h"
> @@ -211,6 +212,17 @@ struct wmax_u32_args {
>
>   struct awcc_priv {
>   	struct wmi_device *wdev;
> +	union {
> +		u32 system_description;
> +		struct {
> +			u8 fan_count;
> +			u8 temp_count;
> +			u8 unknown_count;
> +			u8 profile_count;
> +		} __packed;
> +		u8 res_count[4];
> +	} __packed;
> +
>   	struct device *ppdev;
>   	u8 supported_profiles[PLATFORM_PROFILE_LAST];
>   };
> @@ -614,32 +626,35 @@ static int awcc_platform_profile_probe(void *drvdata, unsigned long *choices)
>   	enum platform_profile_option profile;
>   	struct awcc_priv *priv = drvdata;
>   	enum awcc_thermal_profile mode;
> -	u8 sys_desc[4];
> -	u32 first_mode;
> +	u8 id, offset = 0;
>   	u32 out_data;
>   	int ret;
> -	u8 id;
> -
> -	ret = awcc_thermal_information(priv->wdev, AWCC_OP_GET_SYSTEM_DESCRIPTION,
> -				       0, (u32 *) &sys_desc);
> -	if (ret < 0)
> -		return ret;
> -
> -	first_mode = sys_desc[0] + sys_desc[1];
>
> -	for (u32 i = 0; i < sys_desc[3]; i++) {
> -		ret = awcc_op_get_resource_id(priv->wdev, i + first_mode, &out_data);
> +	/*
> +	 * Thermal profile IDs are listed last at offset
> +	 *	fan_count + temp_count + unknown_count
> +	 */
> +	for (u32 i = 0; i < ARRAY_SIZE(priv->res_count) - 1; i++)
> +		offset += priv->res_count[i];
>
> +	for (u32 i = 0; i < priv->profile_count; i++) {
> +		ret = awcc_op_get_resource_id(priv->wdev, i + offset, &out_data);
>   		if (ret == -EIO)
>   			return ret;
>
> +		/*
> +		 * Some devices report an incorrect number of thermal profiles
> +		 * so the resource ID list may end prematurely
> +		 */
>   		if (ret == -EBADRQC)
>   			break;
>
>   		/* Some IDs have a BIT(8) flag that should be ignored */
>   		id = FIELD_GET(AWCC_RESOURCE_ID_MASK, out_data);
> -		if (!is_awcc_thermal_profile_id(id))
> +		if (!is_awcc_thermal_profile_id(id)) {
> +			dev_dbg(&priv->wdev->dev, "Unmapped thermal profile ID 0x%02x\n", id);
>   			continue;
> +		}
>
>   		mode = FIELD_GET(AWCC_THERMAL_MODE_MASK, id);
>   		profile = awcc_mode_to_platform_profile[mode];
> @@ -680,12 +695,27 @@ static int awcc_platform_profile_init(struct wmi_device *wdev)
>   static int alienware_awcc_setup(struct wmi_device *wdev)
>   {
>   	struct awcc_priv *priv;
> +	u8 tot = 0;
>   	int ret;
>
>   	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
>   	if (!priv)
>   		return -ENOMEM;
>
> +	ret = awcc_thermal_information(wdev, AWCC_OP_GET_SYSTEM_DESCRIPTION,
> +				       0, &priv->system_description);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Sanity check */
> +	for (u32 i = 0; i < ARRAY_SIZE(priv->res_count); i++) {
> +		if (check_add_overflow(tot, priv->res_count[i], &tot)) {

I wonder if it would be easier to just use a int to accumulate all offsets and then check if the resulting value is greater than U8_MAX.

Other than that:

Reviewed-by: Armin Wolf <W_Armin@....de>

> +			dev_err(&wdev->dev, "Malformed system description: %u\n",
> +				priv->system_description);
> +			return -ENXIO;
> +		}
> +	}
> +
>   	priv->wdev = wdev;
>   	dev_set_drvdata(&wdev->dev, priv);
>