Patchwork [1/2,CVE-2012-1601,LUCID] KVM: Clean up error handling during VCPU creation

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Submitter Brad Figg
Date April 26, 2012, 4:37 p.m.
Message ID <1335458259-8920-2-git-send-email-brad.figg@canonical.com>
Download mbox | patch
Permalink /patch/155297/
State New
Headers show

Comments

Brad Figg - April 26, 2012, 4:37 p.m.
From: Jan Kiszka <jan.kiszka@siemens.com>

CVE-2012-1601

BugLink: http://bugs.launchpad.net/bugs/971685

So far kvm_arch_vcpu_setup is responsible for freeing the vcpu struct if
it fails. Move this confusing resonsibility back into the hands of
kvm_vm_ioctl_create_vcpu. Only kvm_arch_vcpu_setup of x86 is affected,
all other archs cannot fail.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
(cherry-pick of d780592b99d7d8a5ff905f6bacca519d4a342c76 upstream)
Signed-off-by: Brad Figg <brad.figg@canonical.com>
---
 arch/x86/kvm/x86.c  |    5 -----
 virt/kvm/kvm_main.c |   11 ++++++-----
 2 files changed, 6 insertions(+), 10 deletions(-)

Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index da48622..aaa3735 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6126,12 +6126,7 @@  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 	if (r == 0)
 		r = kvm_mmu_setup(vcpu);
 	vcpu_put(vcpu);
-	if (r < 0)
-		goto free_vcpu;
 
-	return 0;
-free_vcpu:
-	kvm_x86_ops->vcpu_free(vcpu);
 	return r;
 }
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 087b3f8..fa2321a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1615,18 +1615,18 @@  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 
 	r = kvm_arch_vcpu_setup(vcpu);
 	if (r)
-		return r;
+		goto vcpu_destroy;
 
 	mutex_lock(&kvm->lock);
 	if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
 		r = -EINVAL;
-		goto vcpu_destroy;
+		goto unlock_vcpu_destroy;
 	}
 
 	kvm_for_each_vcpu(r, v, kvm)
 		if (v->vcpu_id == id) {
 			r = -EEXIST;
-			goto vcpu_destroy;
+			goto unlock_vcpu_destroy;
 		}
 
 	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
@@ -1636,7 +1636,7 @@  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	r = create_vcpu_fd(vcpu);
 	if (r < 0) {
 		kvm_put_kvm(kvm);
-		goto vcpu_destroy;
+		goto unlock_vcpu_destroy;
 	}
 
 	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
@@ -1650,8 +1650,9 @@  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	mutex_unlock(&kvm->lock);
 	return r;
 
-vcpu_destroy:
+unlock_vcpu_destroy:
 	mutex_unlock(&kvm->lock);
+vcpu_destroy:
 	kvm_arch_vcpu_destroy(vcpu);
 	return r;
 }