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[Xen-devel] [PATCH] [Mini-OS] Catch NULL dereferences

from [Samuel Thibault]

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Subject:	[Xen-devel] [PATCH] [Mini-OS] Catch NULL dereferences
From:	Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
Date:	Tue, 27 Nov 2007 11:23:05 +0000
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Unmap page 0 (only used early at boot) so as to catch NULL dereferences.

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxx>

diff -r 26e766e0c628 extras/mini-os/arch/x86/mm.c
--- a/extras/mini-os/arch/x86/mm.c      Mon Nov 26 22:28:48 2007 +0000
+++ b/extras/mini-os/arch/x86/mm.c      Tue Nov 27 11:20:32 2007 +0000
@@ -270,6 +270,9 @@ void build_pagetable(unsigned long *star
         start_address += PAGE_SIZE;
     }
 
+    if (HYPERVISOR_update_va_mapping(0, (pte_t) {}, UVMF_INVLPG))
+        printk("Unable to unmap page 0\n");
+
     *start_pfn = pt_pfn;
 }
 

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