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Date: Sat, 21 Oct 2017 01:25:25 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: 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>,
kernel-hardening@...ts.openwall.com,
Kees Cook <keescook@...omium.org>,
Radim Krčmář <rkrcmar@...hat.com>
Subject: [PATCH 2/2] KVM: fix KVM_XEN_HVM_CONFIG ioctl
This ioctl is obsolete (it was used by Xenner as far as I know) but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@...ts.openwall.com
Cc: Kees Cook <keescook@...omium.org>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
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 415529a78c37..c76d7afa30be 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4218,13 +4218,14 @@ 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
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