From: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit c3058d5da2222629bc2223c488a4512b59bb4baf upstream.
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.
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
arch/arm/kvm/mmu.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 2e0357dd8654..f9740851a6a4 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -772,6 +772,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
memslot = gfn_to_memslot(vcpu->kvm, gfn);
+ /* 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, gfn, memslot, fault_status);
if (ret == 0)
ret = 1;
@@ -996,6 +999,14 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
enum kvm_mr_change change)
{
+ /*
+ * Prevent userspace from creating a memory region outside of the IPA
+ * space addressable by the KVM guest IPA space.
+ */
+ if (memslot->base_gfn + memslot->npages >=
+ (KVM_PHYS_SIZE >> PAGE_SHIFT))
+ return -EFAULT;
+
return 0;
}
--
2.3.5
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