Patch "platform/x86: think-lmi: mutex protection around multiple WMI calls" has been added to the 6.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    platform/x86: think-lmi: mutex protection around multiple WMI calls

to the 6.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     platform-x86-think-lmi-mutex-protection-around-multi.patch
and it can be found in the queue-6.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 733b0b0670cbea89ceaf75d7b209f47d5cd61265
Author: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
Date:   Thu Jun 1 16:05:45 2023 -0400

    platform/x86: think-lmi: mutex protection around multiple WMI calls
    
    [ Upstream commit c41e0121a1221894a1a9c4666156db9e1def4d6c ]
    
    When an attribute is being changed if the Admin account is enabled, or if
    a password is being updated then multiple WMI calls are needed.
    Add mutex protection to ensure no race conditions are introduced.
    
    Fixes: b49f72e7f96d ("platform/x86: think-lmi: Certificate authentication support")
    Signed-off-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
    Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230601200552.4396-1-mpearson-lenovo@xxxxxxxxx
    Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 1138f770149d9..6cf77bc26b05b 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -14,6 +14,7 @@
 #include <linux/acpi.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
+#include <linux/mutex.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/dmi.h>
@@ -195,6 +196,7 @@ static const char * const level_options[] = {
 };
 static struct think_lmi tlmi_priv;
 static struct class *fw_attr_class;
+static DEFINE_MUTEX(tlmi_mutex);
 
 /* ------ Utility functions ------------*/
 /* Strip out CR if one is present */
@@ -437,6 +439,9 @@ static ssize_t new_password_store(struct kobject *kobj,
 	/* Strip out CR if one is present, setting password won't work if it is present */
 	strip_cr(new_pwd);
 
+	/* Use lock in case multiple WMI operations needed */
+	mutex_lock(&tlmi_mutex);
+
 	pwdlen = strlen(new_pwd);
 	/* pwdlen == 0 is allowed to clear the password */
 	if (pwdlen && ((pwdlen < setting->minlen) || (pwdlen > setting->maxlen))) {
@@ -493,6 +498,7 @@ static ssize_t new_password_store(struct kobject *kobj,
 		kfree(auth_str);
 	}
 out:
+	mutex_unlock(&tlmi_mutex);
 	kfree(new_pwd);
 	return ret ?: count;
 }
@@ -981,6 +987,9 @@ static ssize_t current_value_store(struct kobject *kobj,
 	/* Strip out CR if one is present */
 	strip_cr(new_setting);
 
+	/* Use lock in case multiple WMI operations needed */
+	mutex_lock(&tlmi_mutex);
+
 	/* Check if certificate authentication is enabled and active */
 	if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) {
 		if (!tlmi_priv.pwd_admin->signature || !tlmi_priv.pwd_admin->save_signature) {
@@ -1039,6 +1048,7 @@ static ssize_t current_value_store(struct kobject *kobj,
 		kobject_uevent(&tlmi_priv.class_dev->kobj, KOBJ_CHANGE);
 	}
 out:
+	mutex_unlock(&tlmi_mutex);
 	kfree(auth_str);
 	kfree(set_str);
 	kfree(new_setting);