Re: [GIT PULL v1 11/23] KVM: s390: Fix unlikely NULL gmap dereference

> When creating a new vCPU, kvm_vm_ioctl_create_vcpu() will call
> kvm_arch_vcpu_postcreate() after the file descriptor for the new vCPU
> has been created. The new file descriptor has not been returned yet,
> but a malicious userspace program could try to guess it.
>=20
> If a malicious userspace program manages to start the newly created vCPU
> before kvm_arch_vcpu_postcreate() is called, __vcpu_run() will try to
> dereference vcpu->arch.gmap and trigger a NULL pointer dereference.
>=20
> Fix this by adding a new field to struct kvm_vcpu_arch to keep track of
> the initialization status of the vCPU. Refuse to run a vCPU that is not
> fully initialized.
>=20
> Fixes: dafd032a15f8 ("KVM: s390: move vcpu specific initalization to a la=
ter point")
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
> Reviewed-by: Steffen Eiden <[email protected]>
> Reviewed-by: Janosch Frank <[email protected]>
> Reviewed-by: Christian Borntraeger <[email protected]>
> Signed-off-by: Claudio Imbrenda <[email protected]>

Sashiko has reviewed this patch and found no issues. It looks great!

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