Re: [PATCH 0/2] KVM: fixes for the kernel-hardening tree

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 23 Oct 2017 11:52:51 +0200
David Hildenbrand <david@redhat.com> wrote:

> On 21.10.2017 01:25, Paolo Bonzini wrote:
> > Two KVM ioctls (KVM_GET/SET_CPUID2) directly access the cpuid_entries
> > field of struct kvm_vcpu_arch.  Therefore, the new usercopy hardening
> > work in linux-next, which forbids copies from and to slab objects
> > unless they are from kmalloc or explicitly whitelisted, breaks KVM
> > completely.
> > 
> > This series fixes it by adding the two new usercopy arguments
> > to kvm_init (more precisely to a new function kvm_init_usercopy,
> > while kvm_init passes zeroes as a default).
> > 
> > There's also another broken ioctl, KVM_XEN_HVM_CONFIG, but it is
> > obsolete and not a big deal at all.
> > 
> > I'm Ccing all submaintainers in case they have something similar
> > going on in their kvm_arch and kvm_vcpu_arch structs.  KVM has a
> > pretty complex userspace API, so thorough with linux-next is highly
> > recommended.  
> 
> I assume on s390x, at least
> 
> kvm_arch_vcpu_ioctl_get_one_reg() and
> kvm_arch_vcpu_ioctl_set_one_reg()
> 
> have to be fixed.

At a glance, seems like it.

> 
> Christian, are you already looking into this?

I'm afraid I'm also busy with travel preparation/travel, so I'd be glad
for any takers.

> 
> > 
> > Many thanks to Thomas Gleixner for reporting this to me.
> > 
> > Paolo
> > 
> > Paolo Bonzini (2):
> >   KVM: allow setting a usercopy region in struct kvm_vcpu
> >   KVM: fix KVM_XEN_HVM_CONFIG ioctl
> > 
> >  arch/x86/include/asm/kvm_host.h |  3 +++
> >  arch/x86/kvm/svm.c              |  4 ++--
> >  arch/x86/kvm/vmx.c              |  4 ++--
> >  arch/x86/kvm/x86.c              | 17 ++++++++++++++---
> >  include/linux/kvm_host.h        | 13 +++++++++++--
> >  virt/kvm/kvm_main.c             | 13 ++++++++-----
> >  6 files changed, 40 insertions(+), 14 deletions(-)
> >   
> 
>