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

From: Cornelia Huck
Date: Mon Oct 23 2017 - 08:39:29 EST


On Mon, 23 Oct 2017 11:52:51 +0200
David Hildenbrand <david@xxxxxxxxxx> 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(-)
> >
>
>