arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE (c3058d5d) · Commits · 戴 / test

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>

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

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