From: Keir Fraser <keir.fraser@citrix.com>
Date: Wed, 28 Nov 2007 12:42:17 +0000 (+0000)
Subject: [Mini-OS] Catch NULL dereferences
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14684^2~10
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=040d9d22870e980154873e99676385dad43c6a92;p=xen.git

[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@citrix.com>
---

diff --git a/extras/mini-os/arch/x86/mm.c b/extras/mini-os/arch/x86/mm.c
index 8d4a8d42fb..70143b3e1a 100644
--- a/extras/mini-os/arch/x86/mm.c
+++ b/extras/mini-os/arch/x86/mm.c
@@ -270,6 +270,9 @@ void build_pagetable(unsigned long *start_pfn, unsigned long *max_pfn)
         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;
 }