[3.8] heimdal: NULL pointer dereference via crafted UDP packets (CVE-2017-17439)
In Heimdal through 7.4, remote unauthenticated attackers are able to
crash the KDC by sending a crafted UDP packet
containing empty data fields for client name or realm. The parser would unconditionally dereference NULL pointers in
that case, leading to a segmentation fault. This is related to the _kdc_as_rep function in kdc/kerberos5.c and
the der_length_visible_string function in lib/asn1/der_length.c.
(from redmine: issue id 8291, created on 2017-12-14, closed on 2018-01-02)
main/heimdal: security fix (CVE-2017-17439) Fixes #8291