KVM: Don't null dereference ops->destroy
[ Upstream commit e8bc2427018826e02add7b0ed0fc625a60390ae5 ] A KVM device cleanup happens in either of two callbacks: 1) destroy() which is called when the VM is being destroyed; 2) release() which is called when a device fd is closed. Most KVM devices use 1) but Book3s's interrupt controller KVM devices (XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during the machine execution. The error handling in kvm_ioctl_create_device() assumes destroy() is always defined which leads to NULL dereference as discovered by Syzkaller. This adds a checks for destroy!=NULL and adds a missing release(). This is not changing kvm_destroy_devices() as devices with defined release() should have been removed from the KVM devices list by then. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -3329,8 +3329,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
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kvm_put_kvm(kvm);
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mutex_lock(&kvm->lock);
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list_del(&dev->vm_node);
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if (ops->release)
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ops->release(dev);
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mutex_unlock(&kvm->lock);
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ops->destroy(dev);
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if (ops->destroy)
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ops->destroy(dev);
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return ret;
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}
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