KVM: MMU: bail out pagewalk on kvm_read_guest error

commit a6085fbaf65ab09bfb5ec8d902d6d21680fe1895 upstream.

Exit the guest pagetable walk loop if reading gpte failed. Otherwise its
possible to enter an endless loop processing the previous present pte.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 85e12cd6fb48b9226052106c9b7c83d97b4bf480..5fa33255348c9fb010191f41cf987e1c4406f917 100644 (file)
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -150,7 +150,9 @@ walk:
                walker->table_gfn[walker->level - 1] = table_gfn;
                walker->pte_gpa[walker->level - 1] = pte_gpa;
 
-               kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte));
+               if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte)))
+                       goto not_present;
+
                trace_kvm_mmu_paging_element(pte, walker->level);
 
                if (!is_present_gpte(pte))