From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932452AbdJZNqC (ORCPT ); Thu, 26 Oct 2017 09:46:02 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:47624 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932425AbdJZNpy (ORCPT ); Thu, 26 Oct 2017 09:45:54 -0400 X-Google-Smtp-Source: ABhQp+TPRZCk2vm6k1R4pK7Mukv1GuaQW4cbNA9NVfVghoz5Zzon0ssFOa3d49l8VOhoRhGh/x4wcg== From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Christoffer Dall , Marc Zyngier , Christian Borntraeger , Cornelia Huck , James Hogan , Paul Mackerras , kernel-hardening@lists.openwall.com, Kees Cook , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH 2/2] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl Date: Thu, 26 Oct 2017 15:45:47 +0200 Message-Id: <20171026134547.23664-3-pbonzini@redhat.com> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171026134547.23664-1-pbonzini@redhat.com> References: <20171026134547.23664-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This ioctl is obsolete (it was used by Xenner as far as I know) but still let's not break it gratuitously... Its handler is copying directly into struct kvm. Go through a bounce buffer instead, with the added benefit that we can actually do something useful with the flags argument---the previous code was exiting with -EINVAL but still doing the copy. This technically is a userspace ABI breakage, but since no one should be using the ioctl, it's a good occasion to see if someone actually complains. Cc: kernel-hardening@lists.openwall.com Cc: Kees Cook Cc: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 272320eb328c..f32fbfb833b3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4187,13 +4187,14 @@ long kvm_arch_vm_ioctl(struct file *filp, mutex_unlock(&kvm->lock); break; case KVM_XEN_HVM_CONFIG: { + struct kvm_xen_hvm_config xhc; r = -EFAULT; - if (copy_from_user(&kvm->arch.xen_hvm_config, argp, - sizeof(struct kvm_xen_hvm_config))) + if (copy_from_user(&xhc, argp, sizeof(xhc))) goto out; r = -EINVAL; - if (kvm->arch.xen_hvm_config.flags) + if (xhc.flags) goto out; + memcpy(&kvm->arch.xen_hvm_config, &xhc, sizeof(xhc)); r = 0; break; } -- 2.14.2 From mboxrd@z Thu Jan 1 00:00:00 1970 Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 26 Oct 2017 15:45:47 +0200 Message-Id: <20171026134547.23664-3-pbonzini@redhat.com> In-Reply-To: <20171026134547.23664-1-pbonzini@redhat.com> References: <20171026134547.23664-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [kernel-hardening] [PATCH 2/2] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Christoffer Dall , Marc Zyngier , Christian Borntraeger , Cornelia Huck , James Hogan , Paul Mackerras , kernel-hardening@lists.openwall.com, Kees Cook , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= List-ID: This ioctl is obsolete (it was used by Xenner as far as I know) but still let's not break it gratuitously... Its handler is copying directly into struct kvm. Go through a bounce buffer instead, with the added benefit that we can actually do something useful with the flags argument---the previous code was exiting with -EINVAL but still doing the copy. This technically is a userspace ABI breakage, but since no one should be using the ioctl, it's a good occasion to see if someone actually complains. Cc: kernel-hardening@lists.openwall.com Cc: Kees Cook Cc: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 272320eb328c..f32fbfb833b3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4187,13 +4187,14 @@ long kvm_arch_vm_ioctl(struct file *filp, mutex_unlock(&kvm->lock); break; case KVM_XEN_HVM_CONFIG: { + struct kvm_xen_hvm_config xhc; r = -EFAULT; - if (copy_from_user(&kvm->arch.xen_hvm_config, argp, - sizeof(struct kvm_xen_hvm_config))) + if (copy_from_user(&xhc, argp, sizeof(xhc))) goto out; r = -EINVAL; - if (kvm->arch.xen_hvm_config.flags) + if (xhc.flags) goto out; + memcpy(&kvm->arch.xen_hvm_config, &xhc, sizeof(xhc)); r = 0; break; } -- 2.14.2