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Message-Id: <15c32f0a-9a51-4f88-7636-182397d7770e@de.ibm.com> Date: Thu, 26 Oct 2017 16:51:38 +0200 From: Christian Borntraeger <borntraeger@...ibm.com> To: Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org Cc: Christoffer Dall <christoffer.dall@...aro.org>, Marc Zyngier <marc.zyngier@....com>, Cornelia Huck <cohuck@...hat.com>, James Hogan <james.hogan@...tec.com>, Paul Mackerras <paulus@...ba.org>, kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>, Christian Borntraeger <borntraeger@...hat.com>, Christoffer Dall <cdall@...aro.org>, Radim Krčmář <rkrcmar@...hat.com> Subject: Re: [PATCH 1/2] kvm: whitelist struct kvm_vcpu_arch On 10/26/2017 03:45 PM, Paolo Bonzini wrote: > On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region > taht is read and written by the KVM_GET/SET_CPUID2 ioctls (x86) > or KVM_GET/SET_ONE_REG (ARM/s390). Without whitelisting the area, > KVM is completely broken on those architectures with usercopy hardening > enabled. > > For now, allow writing to the entire struct on all architectures. > The KVM tree will not refine this to an architecture-specific > subset of struct kvm_vcpu_arch. > > Cc: kernel-hardening@...ts.openwall.com > Cc: Kees Cook <keescook@...omium.org> > Cc: Christian Borntraeger <borntraeger@...hat.com> You wish? Not yet Paolo :-) > Cc: Christoffer Dall <cdall@...aro.org> > Cc: Radim Krčmář <rkrcmar@...hat.com> > Signed-off-by: Paolo Bonzini <pbonzini@...hat.com> Acked-by: Christian Borntraeger <borntraeger@...ibm.com> > --- > virt/kvm/kvm_main.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 4d81f6ded88e..b4809ccfdfa1 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4005,8 +4005,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, > /* A kmem cache lets us meet the alignment requirements of fx_save. */ > if (!vcpu_align) > vcpu_align = __alignof__(struct kvm_vcpu); > - kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align, > - 0, NULL); > + kvm_vcpu_cache = > + kmem_cache_create_usercopy("kvm_vcpu", > + sizeof(struct kvm_vcpu), vcpu_align, > + 0, offsetof(struct kvm_vcpu, arch), > + sizeof_field(struct kvm_vcpu, arch), > + NULL); > if (!kvm_vcpu_cache) { > r = -ENOMEM; > goto out_free_3; >
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