linux-kernel - [PATCH 5.11 190/254] platform/x86: dell-wmi-sysman: Fix possible NULL pointer deref on exit

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Message-Id: <20210329075639.363754680@linuxfoundation.org>
Date:   Mon, 29 Mar 2021 09:58:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Divya Bharathi <Divya_Bharathi@...l.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Alexander Naumann <alexandernaumann@....de>,
        Hans de Goede <hdegoede@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 190/254] platform/x86: dell-wmi-sysman: Fix possible NULL pointer deref on exit

From: Hans de Goede <hdegoede@...hat.com>

[ Upstream commit c59ab4cedab70a1a117a2dba3c48bb78e66c55ca ]

It is possible for release_attributes_data() to get called when the
main_dir_kset has not been created yet, move the removal of the bios-reset
sysfs attr to under a if (main_dir_kset) check to avoid a NULL pointer
deref.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@...l.com>
Cc: Mario Limonciello <mario.limonciello@...l.com>
Reported-by: Alexander Naumann <alexandernaumann@....de>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Link: https://lore.kernel.org/r/20210321115901.35072-3-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/platform/x86/dell-wmi-sysman/sysman.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell-wmi-sysman/sysman.c
index c1997db74cca..8b251b2c37a2 100644
--- a/drivers/platform/x86/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell-wmi-sysman/sysman.c
@@ -225,12 +225,6 @@ static int create_attributes_level_sysfs_files(void)
 	return ret;
 }
 
-static void release_reset_bios_data(void)
-{
-	sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
-	sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &pending_reboot.attr);
-}
-
 static ssize_t wmi_sysman_attr_show(struct kobject *kobj, struct attribute *attr,
 				    char *buf)
 {
@@ -373,8 +367,6 @@ static void destroy_attribute_objs(struct kset *kset)
  */
 static void release_attributes_data(void)
 {
-	release_reset_bios_data();
-
 	mutex_lock(&wmi_priv.mutex);
 	exit_enum_attributes();
 	exit_int_attributes();
@@ -386,12 +378,13 @@ static void release_attributes_data(void)
 		wmi_priv.authentication_dir_kset = NULL;
 	}
 	if (wmi_priv.main_dir_kset) {
+		sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &reset_bios.attr);
+		sysfs_remove_file(&wmi_priv.main_dir_kset->kobj, &pending_reboot.attr);
 		destroy_attribute_objs(wmi_priv.main_dir_kset);
 		kset_unregister(wmi_priv.main_dir_kset);
 		wmi_priv.main_dir_kset = NULL;
 	}
 	mutex_unlock(&wmi_priv.mutex);
-
 }
 
 /**
-- 
2.30.1