From patchwork Mon May 4 01:52:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [for, 3.14.y, stable, 32/47] arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE X-Patchwork-Submitter: Shannon Zhao X-Patchwork-Id: 47970 Message-Id: <1430704362-6292-33-git-send-email-shannon.zhao@linaro.org> To: stable@vger.kernel.org Cc: gregkh@linuxfoundation.org, christoffer.dall@linaro.org, shannon.zhao@linaro.org Date: Mon, 4 May 2015 09:52:27 +0800 From: shannon.zhao@linaro.org List-Id: From: Christoffer Dall 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 Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Shannon Zhao --- 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 8cd0387..8a677ae 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; }