KVM: MMU: bail out pagewalk on kvm_read_guest error

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

Cc: stable@kernel.org
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 58a0f1e88596..ede2131a9225 100644
--- 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))