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-rw-r--r--hurd/hurdinit.c26
1 files changed, 25 insertions, 1 deletions
diff --git a/hurd/hurdinit.c b/hurd/hurdinit.c
index bed78b8321..e7558c3ef7 100644
--- a/hurd/hurdinit.c
+++ b/hurd/hurdinit.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+/* Copyright (C) 1992, 1993, 1994, 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -197,3 +197,27 @@ _hurd_setproc (process_t procserver)
return 0;
}
+
+#ifndef PIC
+
+/* Map the page at address zero with no access allowed, so
+ dereferencing NULL will fault and no "anywhere" allocations
+ (e.g. the out of line memory containing the argument strings)
+ can be assigned address zero, which C says is not a valid pointer.
+
+ When dynamically linked, this will be done by the dynamic linker
+ before we run. */
+
+static void map0 (void) __attribute__ ((unused));
+text_set_element (_hurd_preinit_hook, map0);
+
+static void
+map0 (void)
+{
+ vm_address_t addr = 0;
+ __vm_map (__mach_task_self (),
+ &addr, __vm_page_size, 0, 0, MACH_PORT_NULL, 0, 1,
+ VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);
+}
+
+#endif