On Tue, Sep 30, 2014 at 01:46:51PM +0100, Catalin Marinas wrote: > On Thu, Sep 25, 2014 at 08:42:54PM +0100, Christoffer Dall wrote: > > 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. > > > > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > > --- > > arch/arm/kvm/mmu.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > > index 4532f5f..52a311a 100644 > > --- a/arch/arm/kvm/mmu.c > > +++ b/arch/arm/kvm/mmu.c > > @@ -975,6 +975,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > > goto out_unlock; > > } > > > > + /* Userspace should not be able to register out-of-bounds IPAs */ > > I think "userspace" is a bit misleading (should be "guests"). > see below > > + VM_BUG_ON(fault_ipa >= KVM_PHYS_SIZE); > > Can guests not generate IPA addresses higher than KVM_PHYS_SIZE? I don't > see why this wouldn't be possible when PARange > 40. > Guests can, but higher in this function we resolve the the gfn (IPA) to a memslot (hva). That only succeeds if userspace actually managed to register a memslot with such an IPA, which we prevent in the other part of this patch. So if we get here, it's a bug, because we should have entered the section above and taken the goto out_unlock. Makes sense? Thanks, -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
