An issue was discovered in the Linux kernel through 5.2.13. nbd_genl_status in drivers/block/nbd.c does not check the nla_nest_start_noflag return value.
https://usn.ubuntu.com/4440-1/
https://usn.ubuntu.com/4439-1/
https://usn.ubuntu.com/4425-1/
https://usn.ubuntu.com/4414-1/
https://support.f5.com/csp/article/K03814795?utm_source=f5support&%3Butm_medium=RSS
https://security.netapp.com/advisory/ntap-20191004-0001/