| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 056/129] arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE | Date | Fri, 22 May 2015 09:57:21 +0100 |
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3.16.7-ckt12 -stable review patch. If anyone has any objections, please let me know.
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From: Christoffer Dall <christoffer.dall@linaro.org>
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@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org> [ luis: backported to 3.16: used shannon's backport for 3.14 ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- 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 0258b22bf9d1..2555a52cccd2 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -926,6 +926,9 @@ 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, memslot, fault_status); if (ret == 0) ret = 1; @@ -1150,6 +1153,14 @@ 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; }
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