When creating or moving a memslot, make sure the IPA space is within the
addressable range of the guest. Otherwise, user space can create too
large a memslot and KVM would try to access potentially unallocated page
table entries when inserting entries in the Stage-2 page tables.
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
---
arch/arm/kvm/mmu.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 4532f5f..52a311a 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -975,6 +975,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
goto out_unlock;
}
+ /* Userspace should not be able to register out-of-bounds IPAs */
+ VM_BUG_ON(fault_ipa >= KVM_PHYS_SIZE);
+
ret = user_mem_abort(vcpu, fault_ipa, memslot, hva, fault_status);
if (ret == 0)
ret = 1;
@@ -1201,6 +1204,11 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
enum kvm_mr_change change)
{
+ if (change == KVM_MR_CREATE || change == KVM_MR_MOVE) {
+ if (memslot->base_gfn + memslot->npages >=
+ (KVM_PHYS_SIZE >> PAGE_SHIFT))
+ return -EFAULT;
+ }
return 0;
}
--
2.0.0
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