From: Alexey Kardashevskiy aik@ozlabs.ru
commit e8bc2427018826e02add7b0ed0fc625a60390ae5 upstream.
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: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/kvm_main.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4172,8 +4172,11 @@ static int kvm_ioctl_create_device(struc kvm_put_kvm_no_destroy(kvm); mutex_lock(&kvm->lock); list_del(&dev->vm_node); + if (ops->release) + ops->release(dev); mutex_unlock(&kvm->lock); - ops->destroy(dev); + if (ops->destroy) + ops->destroy(dev); return ret; }