KVM: s390: check cpu_id prior to using it

commit 4d47555a80495657161a7e71ec3014ff2021e450 upstream.

We use the cpu id provided by userspace as array index here. Thus we
clearly need to check it first. Ooops.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index dc2b580e27bcfc45e0a883ffd61992d4647eb64c..0cba935d1282ed20e09353bf5419d06246330e37 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -312,11 +312,17 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
                                      unsigned int id)
 {
-       struct kvm_vcpu *vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL);
-       int rc = -ENOMEM;
+       struct kvm_vcpu *vcpu;
+       int rc = -EINVAL;
+
+       if (id >= KVM_MAX_VCPUS)
+               goto out;
+
+       rc = -ENOMEM;
 
+       vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL);
        if (!vcpu)
-               goto out_nomem;
+               goto out;
 
        vcpu->arch.sie_block = (struct kvm_s390_sie_block *)
                                        get_zeroed_page(GFP_KERNEL);
@@ -352,7 +358,7 @@ out_free_sie_block:
        free_page((unsigned long)(vcpu->arch.sie_block));
 out_free_cpu:
        kfree(vcpu);
-out_nomem:
+out:
        return ERR_PTR(rc);
 }