[PATCH] selinux: fix sb_lock/sb_security_lock nesting

From: Stephen Smalley <sds@tycho.nsa.gov>

Fix unsafe nesting of sb_lock inside sb_security_lock in
selinux_complete_init.  Detected by the kernel locking validator.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 21dad41..90b4cdc 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4422,6 +4422,7 @@ void selinux_complete_init(void)
 
        /* Set up any superblocks initialized prior to the policy load. */
        printk(KERN_INFO "SELinux:  Setting up existing superblocks.\n");
+       spin_lock(&sb_lock);
        spin_lock(&sb_security_lock);
 next_sb:
        if (!list_empty(&superblock_security_head)) {
@@ -4430,19 +4431,20 @@ next_sb:
                                           struct superblock_security_struct,
                                           list);
                struct super_block *sb = sbsec->sb;
-               spin_lock(&sb_lock);
                sb->s_count++;
-               spin_unlock(&sb_lock);
                spin_unlock(&sb_security_lock);
+               spin_unlock(&sb_lock);
                down_read(&sb->s_umount);
                if (sb->s_root)
                        superblock_doinit(sb, NULL);
                drop_super(sb);
+               spin_lock(&sb_lock);
                spin_lock(&sb_security_lock);
                list_del_init(&sbsec->list);
                goto next_sb;
        }
        spin_unlock(&sb_security_lock);
+       spin_unlock(&sb_lock);
 }
 
 /* SELinux requires early initialization in order to label