releases/3.1.1/kvm-s390-check-cpu_id-prior-to-using-it.patch

From 4d47555a80495657161a7e71ec3014ff2021e450 Mon Sep 17 00:00:00 2001
From: Carsten Otte <cotte@de.ibm.com>
Date: Tue, 18 Oct 2011 12:27:12 +0200
Subject: KVM: s390: check cpu_id prior to using it

From: Carsten Otte <cotte@de.ibm.com>

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>

---
 arch/s390/kvm/kvm-s390.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- 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
 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);
 }