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authorMarcelo Tosatti <mtosatti@redhat.com>2008-11-25 15:33:10 +0100
committerAvi Kivity <avi@redhat.com>2008-11-26 12:34:27 +0200
commit6c475352e87224a8f0b8cc6f6cc96b30563dc5b4 (patch)
tree1046e74c244c3db4673fb937af8b56875405114c
parentc30f8a6c6d74f67bc2107726cc61a1e7c71e9740 (diff)
KVM: MMU: avoid creation of unreachable pages in the shadow
It is possible for a shadow page to have a parent link pointing to a freed page. When zapping a high level table, kvm_mmu_page_unlink_children fails to remove the parent_pte link. For that to happen, the child must be unreachable via the shadow tree, which can happen in shadow_walk_entry if the guest pte was modified in between walk() and fetch(). Remove the parent pte reference in such case. Possible cause for oops in bug #2217430. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
-rw-r--r--arch/x86/kvm/paging_tmpl.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 613ec9aa674..84eee43bbe7 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -331,6 +331,7 @@ static int FNAME(shadow_walk_entry)(struct kvm_shadow_walk *_sw,
r = kvm_read_guest_atomic(vcpu->kvm, gw->pte_gpa[level - 2],
&curr_pte, sizeof(curr_pte));
if (r || curr_pte != gw->ptes[level - 2]) {
+ kvm_mmu_put_page(shadow_page, sptep);
kvm_release_pfn_clean(sw->pfn);
sw->sptep = NULL;
return 1;