fix REQ-42

arch/x86/kernel/syscall.c

@@ -1208,6 +1208,18 @@ set_signal(int sig, void *regs0, siginfo_t *info)
 		do_kill(thread, thread->proc->pid, thread->tid, sig, info, 0);
 }
 
+int
+arch_range_check(unsigned long addr)
+{
+	struct thread *thread = cpu_local_var(current);
+	struct vm_regions *region = &thread->vm->region;
+
+	if(addr < region->user_start ||
+	   addr > region->user_end)
+		return -EINVAL;
+	return 0;
+}
+
 SYSCALL_DECLARE(mmap)
 {
 	const int supported_flags = 0