dhcp6: make sure we have enough space for the DHCP6 option header
Fixes a vulnerability originally discovered by Felix Wilhelm from
Google.
CVE-2018-15688
LP: #1795921
https://bugzilla.redhat.com/show_bug.cgi?id=1639067
(cherry-picked from commit 4dac5eaba4e419b29c97da38a8b1f82336c2c892)
Resolves: #1643363
patch_name: 0034-dhcp6-make-sure-we-have-enough-space-for-the-DHCP6-o.patch
present_in_specfile: true
location_in_specfile: 34
squash_commits: true