um: wrong sigmask saved in case of multiple sigframes

we can't just find oldmask once; if there are multiple signals
and we loop building sigframes for those, ->saved_mask will be
definitely wrong for all but the first one.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/um/kernel/signal.c

@@ -74,15 +74,14 @@ static int kern_do_signal(struct pt_regs *regs)
 {
 	struct k_sigaction ka_copy;
 	siginfo_t info;
-	sigset_t *oldset;
 	int sig, handled_sig = 0;
 
-	if (test_thread_flag(TIF_RESTORE_SIGMASK))
-		oldset = &current->saved_sigmask;
-	else
-		oldset = &current->blocked;
-
 	while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
+		sigset_t *oldset;
+		if (test_thread_flag(TIF_RESTORE_SIGMASK))
+			oldset = &current->saved_sigmask;
+		else
+			oldset = &current->blocked;
 		handled_sig = 1;
 		/* Whee!  Actually deliver the signal.  */
 		if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {