[PATCH v2 05/10] platform/x86: alienware-wmi-wmax: Improve platform profile probe

[Kurt Borja <kuurtb@gmail.com>]

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.

While at it, replace set_bit() with it's non-atomic version __set_bit()
because `choices` belong to this thread only.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
---
 .../platform/x86/dell/alienware-wmi-wmax.c    | 61 ++++++++++++++-----
 1 file changed, 46 insertions(+), 15 deletions(-)

diff --git a/drivers/platform/x86/dell/alienware-wmi-wmax.c b/drivers/platform/x86/dell/alienware-wmi-wmax.c
index 4a8335d90b5d..965b427f8f0a 100644
--- a/drivers/platform/x86/dell/alienware-wmi-wmax.c
+++ b/drivers/platform/x86/dell/alienware-wmi-wmax.c
@@ -37,6 +37,9 @@
 #define AWCC_THERMAL_MODE_MASK			GENMASK(3, 0)
 #define AWCC_RESOURCE_ID_MASK			GENMASK(7, 0)
 
+/* Arbitrary limit based on supported models */
+#define AWCC_MAX_RES_COUNT			16
+
 static bool force_platform_profile;
 module_param_unsafe(force_platform_profile, bool, 0);
 MODULE_PARM_DESC(force_platform_profile, "Forces auto-detecting thermal profiles without checking if WMI thermal backend is available");
@@ -211,6 +214,17 @@ 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];
 };
@@ -614,38 +628,41 @@ 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 (unsigned int i = 0; i < ARRAY_SIZE(priv->res_count) - 1; i++)
+		offset += priv->res_count[i];
 
+	for (unsigned int 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];
 		priv->supported_profiles[profile] = id;
 
-		set_bit(profile, choices);
+		__set_bit(profile, choices);
 	}
 
 	if (bitmap_empty(choices, PLATFORM_PROFILE_LAST))
@@ -655,7 +672,7 @@ static int awcc_platform_profile_probe(void *drvdata, unsigned long *choices)
 		priv->supported_profiles[PLATFORM_PROFILE_PERFORMANCE] =
 			AWCC_THERMAL_MODE_GMODE;
 
-		set_bit(PLATFORM_PROFILE_PERFORMANCE, choices);
+		__set_bit(PLATFORM_PROFILE_PERFORMANCE, choices);
 	}
 
 	return 0;
@@ -686,6 +703,20 @@ static int alienware_awcc_setup(struct wmi_device *wdev)
 	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 (unsigned int i = 0; i < ARRAY_SIZE(priv->res_count); i++) {
+		if (priv->res_count[i] > AWCC_MAX_RES_COUNT) {
+			dev_err(&wdev->dev, "Malformed system description: 0x%08x\n",
+				priv->system_description);
+			return -ENXIO;
+		}
+	}
+
 	priv->wdev = wdev;
 	dev_set_drvdata(&wdev->dev, priv);
 
-- 
2.48.1