From 46515736f8687c5dbde5637ca2f2678055c9c0f7 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 26 Oct 2017 15:45:46 +0200 Subject: [PATCH] kvm: whitelist struct kvm_vcpu_arch MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On x86, ARM and s390, struct kvm_vcpu_arch has a usercopy region that 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@lists.openwall.com Cc: Kees Cook Cc: Christian Borntraeger Cc: Christoffer Dall Cc: Radim Krčmář Signed-off-by: Paolo Bonzini Acked-by: Christoffer Dall Acked-by: Marc Zyngier Acked-by: Christian Borntraeger Signed-off-by: Kees Cook --- 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 c422c10cd1dd..96689967f5c3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4029,8 +4029,12 @@ 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, - SLAB_ACCOUNT, NULL); + kvm_vcpu_cache = + kmem_cache_create_usercopy("kvm_vcpu", vcpu_size, vcpu_align, + SLAB_ACCOUNT, + offsetof(struct kvm_vcpu, arch), + sizeof_field(struct kvm_vcpu, arch), + NULL); if (!kvm_vcpu_cache) { r = -ENOMEM; goto out_free_3; -- GitLab