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Message-ID: <20180409002738.163941-109-alexander.levin@microsoft.com>
Date: Mon, 9 Apr 2018 00:29:07 +0000
From: Sasha Levin <Alexander.Levin@...rosoft.com>
To: "stable@...r.kernel.org" <stable@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Paolo Bonzini <pbonzini@...hat.com>, "kernel-hardening@...ts.openwall.com"
<kernel-hardening@...ts.openwall.com>, Kees Cook <keescook@...omium.org>,
Radim Krčmář <rkrcmar@...hat.com>, Sasha Levin
<Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.4 109/162] kvm: x86: fix KVM_XEN_HVM_CONFIG
ioctl
From: Paolo Bonzini <pbonzini@...hat.com>
[ Upstream commit 51776043afa415435c7e4636204fbe4f7edc4501 ]
This ioctl is obsolete (it was used by Xenner as far as I know) but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>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.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 f37f0c72b22a..9cea09597d66 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3973,13 +3973,14 @@ 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;
}
--
2.15.1
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