commit fd15a59b20220a2d89d628ecebfcaad1ddefe871
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Wed Apr 16 23:16:15 2014 +0200

    hurd: Do not allow unmapping address 0
    
    	* sysdeps/mach/munmap.c (__munmap): Return EINVAL if `addr' is 0.

diff --git a/sysdeps/mach/munmap.c b/sysdeps/mach/munmap.c
index f8c416f..cfd5daa 100644
--- a/sysdeps/mach/munmap.c
+++ b/sysdeps/mach/munmap.c
@@ -27,6 +27,13 @@ int
 __munmap (__ptr_t addr, size_t len)
 {
   kern_return_t err;
+
+  if (addr == 0)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
   if (err = __vm_deallocate (__mach_task_self (),
 			     (vm_address_t) addr, (vm_size_t) len))
     {