From: Christoffer Dall Date: Fri, 10 Oct 2014 10:14:29 +0000 (+0200) Subject: arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE X-Git-Tag: v3.14.47~11 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02524d7e8bc8e72e4813eb7de44c52be1ce6d73b;p=linux arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE commit c3058d5da2222629bc2223c488a4512b59bb4baf upstream. [Since we don't backport commit 8eef912 (arm/arm64: KVM: map MMIO regions at creation time) for linux-3.14.y, the context of this patch is different, while the change itself is same.] 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: Greg Kroah-Hartman --- diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 8cd03872c83d..d12277249fa2 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; }