[Xen-changelog] [xen-unstable] [Mini-OS] Catch NULL dereferences

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1196253737 0
# Node ID 3fdbdd131fc7c64cacf99e2dd9eda40ca3ed40bb
# Parent  74bd94747ca31fae0616f8ecc36b389867fb13ed
[Mini-OS] Catch NULL dereferences

Unmap page 0 (only used early at boot) so as to catch NULL dereferences.

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxx>
---
 extras/mini-os/arch/x86/mm.c |    3 +++
 1 files changed, 3 insertions(+)

diff -r 74bd94747ca3 -r 3fdbdd131fc7 extras/mini-os/arch/x86/mm.c
--- a/extras/mini-os/arch/x86/mm.c      Wed Nov 28 12:41:41 2007 +0000
+++ b/extras/mini-os/arch/x86/mm.c      Wed Nov 28 12:42:17 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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