posix_timer: Fix error path in timer_create

commit 45e0fff upstream.

Move CLOCK_DISPATCH(which_clock, timer_create, (new_timer)) after all
posible EFAULT erros.

*_timer_create may allocate/get resources.
(for example posix_cpu_timer_create does get_task_struct)

[ tglx: fold the remove crappy comment patch into this ]

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Pavel Emelyanov <xemul@openvz.org>
Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

kernel/posix-timers.c

@@ -524,14 +524,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 	new_timer->it_id = (timer_t) new_timer_id;
 	new_timer->it_clock = which_clock;
 	new_timer->it_overrun = -1;
-	error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
-	if (error)
-		goto out;
 
-	/*
-	 * return the timer_id now.  The next step is hard to
-	 * back out if there is an error.
-	 */
 	if (copy_to_user(created_timer_id,
 			 &new_timer_id, sizeof (new_timer_id))) {
 		error = -EFAULT;
@@ -562,6 +555,10 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 	new_timer->sigq->info.si_tid   = new_timer->it_id;
 	new_timer->sigq->info.si_code  = SI_TIMER;
 
+	error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
+	if (error)
+		goto out;
+
 	spin_lock_irq(&current->sighand->siglock);
 	new_timer->it_signal = current->signal;
 	list_add(&new_timer->list, &current->signal->posix_timers);