From fd40ffc72e2f74c7db61e400903e7d50a88bc0b0 Mon Sep 17 00:00:00 2001
From: Stephen Smalley <sds@tycho.nsa.gov>
Date: Mon, 9 Apr 2018 14:36:05 -0400
Subject: selinux: fix missing dput() before selinuxfs unmount

Commit 0619f0f5e36f ("selinux: wrap selinuxfs state") triggers a BUG
when SELinux is runtime-disabled (i.e. systemd or equivalent disables
SELinux before initial policy load via /sys/fs/selinux/disable based on
/etc/selinux/config SELINUX=disabled).

This does not manifest if SELinux is disabled via kernel command line
argument or if SELinux is enabled (permissive or enforcing).

Before:
  SELinux:  Disabled at runtime.
  BUG: Dentry 000000006d77e5c7{i=17,n=null}  still in use (1) [unmount of selinuxfs selinuxfs]

After:
  SELinux:  Disabled at runtime.

Fixes: 0619f0f5e36f ("selinux: wrap selinuxfs state")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 security/selinux/selinuxfs.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'security')

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 4be683eeba01..245160373dab 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -2061,6 +2061,7 @@ __initcall(init_sel_fs);
 void exit_sel_fs(void)
 {
 	sysfs_remove_mount_point(fs_kobj, "selinux");
+	dput(selinux_null.dentry);
 	kern_unmount(selinuxfs_mount);
 	unregister_filesystem(&sel_fs_type);
 }
-- 
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