selinux: various sparse fixes

When running the SELinux code through sparse, there are a handful of
warnings.  This patch resolves some of these warnings caused by
"__rcu" mismatches.

 % make W=1 C=1 security/selinux/

Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -2553,7 +2553,7 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
 	if (rc) {
 		clear_itimer();
 
-		spin_lock_irq(&current->sighand->siglock);
+		spin_lock_irq(&unrcu_pointer(current->sighand)->siglock);
 		if (!fatal_signal_pending(current)) {
 			flush_sigqueue(&current->pending);
 			flush_sigqueue(&current->signal->shared_pending);
@@ -2561,13 +2561,13 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
 			sigemptyset(&current->blocked);
 			recalc_sigpending();
 		}
-		spin_unlock_irq(&current->sighand->siglock);
+		spin_unlock_irq(&unrcu_pointer(current->sighand)->siglock);
 	}
 
 	/* Wake up the parent if it is waiting so that it can recheck
 	 * wait permission to the new task SID. */
 	read_lock(&tasklist_lock);
-	__wake_up_parent(current, current->real_parent);
+	__wake_up_parent(current, unrcu_pointer(current->real_parent));
 	read_unlock(&tasklist_lock);
 }
 

security/selinux/ibpkey.c

@@ -104,7 +104,7 @@ static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
 
 		tail = list_entry(
 			rcu_dereference_protected(
-				sel_ib_pkey_hash[idx].list.prev,
+				list_tail_rcu(&sel_ib_pkey_hash[idx].list),
 				lockdep_is_held(&sel_ib_pkey_lock)),
 			struct sel_ib_pkey, list);
 		list_del_rcu(&tail->list);

security/selinux/netnode.c

@@ -164,7 +164,8 @@ static void sel_netnode_insert(struct sel_netnode *node)
 	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
 		struct sel_netnode *tail;
 		tail = list_entry(
-			rcu_dereference_protected(sel_netnode_hash[idx].list.prev,
+			rcu_dereference_protected(
+				list_tail_rcu(&sel_netnode_hash[idx].list),
 				lockdep_is_held(&sel_netnode_lock)),
 			struct sel_netnode, list);
 		list_del_rcu(&tail->list);

security/selinux/netport.c

@@ -113,7 +113,7 @@ static void sel_netport_insert(struct sel_netport *port)
 		struct sel_netport *tail;
 		tail = list_entry(
 			rcu_dereference_protected(
-				sel_netport_hash[idx].list.prev,
+				list_tail_rcu(&sel_netport_hash[idx].list),
 				lockdep_is_held(&sel_netport_lock)),
 			struct sel_netport, list);
 		list_del_rcu(&tail->list);