[PATCH 6.4 458/800] platform/x86: think-lmi: mutex protection around multiple WMI calls

Greg Kroah-Hartman
2023-07-16T20:15:07Z

From: Mark Pearson <mpearson-lenovo@squebb.ca>

[ 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@squebb.ca>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230601200552.4396-1-mpearson-lenovo@squebb.ca
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/platform/x86/think-lmi.c | 10 ++++++++++
1 file changed, 10 insertions(+)

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);
--
2.39.2