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

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Date:   Sat, 21 Oct 2017 01:25:23 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     kernel-hardening@...ts.openwall.com,
        Kees Cook <keescook@...omium.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Cornelia Huck <cohuck@...hat.com>,
        James Hogan <james.hogan@...tec.com>,
        Paul Mackerras <paulus@...ba.org>
Subject: [PATCH 0/2] KVM: fixes for the kernel-hardening tree

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There's also another broken ioctl, KVM_XEN_HVM_CONFIG, but it is
obsolete and not a big deal at all.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.

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(-)

-- 
2.14.2