Patch "arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-arm64-kvm-ensure-memslots-are-within-kvm_phys_size.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Christoffer Dall <[email protected]>
Date: Fri, 10 Oct 2014 12:14:29 +0200
Subject: arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE

From: Christoffer Dall <[email protected]>

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.

---
 arch/arm/kvm/mmu.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

@@ -926,6 +926,9 @@ int kvm_handle_guest_abort(struct kvm_vc
 
 	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(struc
 				   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;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/arm-arm64-kvm-ensure-memslots-are-within-kvm_phys_size.patch queue-3.14/arm-arm64-kvm-fix-potential-null-dereference-in.patch queue-3.14/arm64-kvm-fix-unmapping-with-48-bit-vas.patch queue-3.14/arm-arm64-kvm-fix-set_clear_sgi_pend_reg-offset.patch queue-3.14/arm-kvm-strict_mm_typechecks-fix-for-user_mem_abort.patch queue-3.14/arm-arm64-kvm-fix-use-of-wnr-bit-in-kvm_is_write_fault.patch queue-3.14/arm-kvm-fix-cpu-hotplug.patch queue-3.14/arm-arm64-kvm-fix-vttbr_baddr_mask-and-pgd-alloc.patch queue-3.14/arm-arm64-kvm-vgic-fix-error-code-in-kvm_vgic_create.patch queue-3.14/kvm-arm-vgic-plug-irq-injection-race.patch