The rngapi_reset function in crypto/rng.c in the Linux kernel before 4.2 allows attackers to cause a denial of service (NULL pointer dereference).
https://github.com/torvalds/linux/commit/94f1bb15bed84ad6c893916b7e7b9db6f1d7eec6
https://bugzilla.redhat.com/show_bug.cgi?id=1514609
https://bugzilla.redhat.com/show_bug.cgi?id=1485815
https://access.redhat.com/errata/RHSA-2018:1062