From db9ad21d272a4dce53c35095b97ca0a597b45004 Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Mon, 22 Sep 2014 17:59:57 +0200
Subject: exec: redzone page zero before loading anything

This prevents load_section from mapping any sections to page zero.

* exec/exec.c (do_exec): Redzone page zero before loading anything.
---
 exec/exec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/exec/exec.c b/exec/exec.c
index 2fc1e441..0ecf2d3e 100644
--- a/exec/exec.c
+++ b/exec/exec.c
@@ -1116,6 +1116,16 @@ do_exec (file_t file,
 	mach_port_destroy (oldtask, destroynames[i]);
     }
 
+  /* Map page zero redzoned.  */
+  {
+    vm_address_t addr = 0;
+    e.error = vm_map (newtask,
+		      &addr, vm_page_size, 0, 0, MACH_PORT_NULL, 0, 1,
+		      VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);
+    if (e.error)
+      goto out;
+  }
+
 /* XXX this should be below
    it is here to work around a vm_map kernel bug. */
   if (interp.file != MACH_PORT_NULL)
-- 
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