[PATCH AUTOSEL for 4.4 109/162] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl

[Sasha Levin]

From: Paolo Bonzini 

[ 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This ioctl is obsolete (it was used by Xenner as far as I know) but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-harden...@lists.openwall.com
Cc: Kees Cook 
Cc: Radim Krčmář 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Kees Cook 
Signed-off-by: Sasha Levin 
---
 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(>lock);
break;
case KVM_XEN_HVM_CONFIG: {
+   struct kvm_xen_hvm_config xhc;
r = -EFAULT;
-   if (copy_from_user(>arch.xen_hvm_config, argp,
-  sizeof(struct kvm_xen_hvm_config)))
+   if (copy_from_user(, argp, sizeof(xhc)))
goto out;
r = -EINVAL;
-   if (kvm->arch.xen_hvm_config.flags)
+   if (xhc.flags)
goto out;
+   memcpy(>arch.xen_hvm_config, , sizeof(xhc));
r = 0;
break;
}
-- 
2.15.1

[PATCH AUTOSEL for 4.4 109/162] kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl

[Sasha Levin]

From: Paolo Bonzini 

[ 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This ioctl is obsolete (it was used by Xenner as far as I know) but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-harden...@lists.openwall.com
Cc: Kees Cook 
Cc: Radim Krčmář 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Kees Cook 
Signed-off-by: Sasha Levin 
---
 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(>lock);
break;
case KVM_XEN_HVM_CONFIG: {
+   struct kvm_xen_hvm_config xhc;
r = -EFAULT;
-   if (copy_from_user(>arch.xen_hvm_config, argp,
-  sizeof(struct kvm_xen_hvm_config)))
+   if (copy_from_user(, argp, sizeof(xhc)))
goto out;
r = -EINVAL;
-   if (kvm->arch.xen_hvm_config.flags)
+   if (xhc.flags)
goto out;
+   memcpy(>arch.xen_hvm_config, , sizeof(xhc));
r = 0;
break;
}
-- 
2.15.1