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arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE

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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@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Christoffer Dall 2014-10-10 12:14:29 +02:00
parent 38f791a4e4
commit c3058d5da2
1 changed files with 11 additions and 0 deletions
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11
arch/arm/kvm/mmu.c
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@ -1003,6 +1003,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
goto out_unlock; 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); ret = user_mem_abort(vcpu, fault_ipa, memslot, hva, fault_status);
if (ret == 0) if (ret == 0)
ret = 1; ret = 1;
@ -1228,6 +1231,14 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
if (change != KVM_MR_CREATE && change != KVM_MR_MOVE) if (change != KVM_MR_CREATE && change != KVM_MR_MOVE)
return 0; return 0;
/*
* 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;
/* /*
* A memory region could potentially cover multiple VMAs, and any holes * A memory region could potentially cover multiple VMAs, and any holes
* between them, so iterate over all of them to find out if we can map * between them, so iterate over all of them to find out if we can map