3.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
commit c3058d5da2222629bc2223c488a4512b59bb4baf upstream.
[Since we don't backport commit 8eef912 (arm/arm64: KVM: map MMIO regions
at creation time) for linux-3.14.y, the context of this patch is
different, while the change itself is same.]
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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kvm/mmu.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -926,6 +926,9 @@ int kvm_handle_guest_abort(struct kvm_vc
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, memslot, fault_status);
if (ret == 0)
ret = 1;
@@ -1150,6 +1153,14 @@ int kvm_arch_prepare_memory_region(struc
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;
}
--
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