platform/x86: think-lmi: Abort probe on analyze failure

[ Upstream commit 812fcc6095 ]

A Lenovo ThinkStation S20 (4157CTO BIOS 60KT41AUS) fails to boot on
recent kernels including the think-lmi driver, due to the fact that
errors returned by the tlmi_analyze() function are ignored by
tlmi_probe(), where  tlmi_sysfs_init() is called unconditionally.
This results in making use of an array of already freed, non-null
pointers and other uninitialized globals, causing all sorts of nasty
kobject and memory faults.

Make use of the analyze function return value, free a couple leaked
allocations, and remove the settings_count field, which is incremented
but never consumed.

Fixes: a40cd7ef22 ("platform/x86: think-lmi: Add WMI interface support on Lenovo platforms")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Mark Gross <markgross@kernel.org>
Reviewed-by: Mark Pearson <markpearson@lenovo.com>
Link: https://lore.kernel.org/r/163639463588.1330483.15850167112490200219.stgit@omen
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/platform/x86/think-lmi.c

@@ -888,8 +888,10 @@ static int tlmi_analyze(void)
 			break;
 		if (!item)
 			break;
-		if (!*item)
+		if (!*item) {
+			kfree(item);
 			continue;
+		}
 
 		/* It is not allowed to have '/' for file name. Convert it into '\'. */
 		strreplace(item, '/', '\\');
@@ -902,6 +904,7 @@ static int tlmi_analyze(void)
 		setting = kzalloc(sizeof(*setting), GFP_KERNEL);
 		if (!setting) {
 			ret = -ENOMEM;
+			kfree(item);
 			goto fail_clear_attr;
 		}
 		setting->index = i;
@@ -916,7 +919,6 @@ static int tlmi_analyze(void)
 		}
 		kobject_init(&setting->kobj, &tlmi_attr_setting_ktype);
 		tlmi_priv.setting[i] = setting;
-		tlmi_priv.settings_count++;
 		kfree(item);
 	}
 
@@ -983,7 +985,12 @@ static void tlmi_remove(struct wmi_device *wdev)
 
 static int tlmi_probe(struct wmi_device *wdev, const void *context)
 {
-	tlmi_analyze();
+	int ret;
+
+	ret = tlmi_analyze();
+	if (ret)
+		return ret;
+
 	return tlmi_sysfs_init();
 }
 

drivers/platform/x86/think-lmi.h

@@ -55,7 +55,6 @@ struct tlmi_attr_setting {
 struct think_lmi {
 	struct wmi_device *wmi_device;
 
-	int settings_count;
 	bool can_set_bios_settings;
 	bool can_get_bios_selections;
 	bool can_set_bios_password;