From 91a82540f3e417f9fb908bcacffc8c8d27c59078 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Fri, 10 Oct 2014 12:14:29 +0200 Subject: [PATCH] arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE 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 Signed-off-by: Jiri Slaby --- 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 2e0357dd86548..f9740851a6a4a 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -772,6 +772,9 @@ 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, gfn, memslot, fault_status); if (ret == 0) ret = 1; @@ -996,6 +999,14 @@ 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; } -- 2.47.3