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Commit c3058d5d authored by Christoffer Dall's avatar Christoffer Dall
Browse files

arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE 



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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent 38f791a4

arch/arm/kvm/mmu.c

+11 −0
Original line number Diff line number Diff line
@@ -1003,6 +1003,9 @@ 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;
@@ -1228,6 +1231,14 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE)

		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

	 * between them, so iterate over all of them to find out if we can map