opensmtpd: multiple issues

an oversight in the portable version of fgetln() that allows attackers
to read and write out-of-bounds memory

multiple denial-of-service vulnerabilities that allow local users to
kill or hang OpenSMTPD

a stack-based buffer overflow that allows local users to crash
OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user

a hardlink attack (or race-conditioned symlink attack) that allows
local users to unset the chflags() of arbitrary files

a hardlink attack that allows local users to read the first line of
arbitrary files (for example, root’s hash from /etc/master.passwd)

a denial-of-service vulnerability that allows remote attackers to fill
OpenSMTPD’s queue or mailbox hard-disk partition

an out-of-bounds memory read that allows remote attackers to crash
OpenSMTPD, or leak information and defeat the ASLR protection

a use-after-free vulnerability that allows remote attackers to crash
OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user

fix an mda buffer truncation bug which allows a user to create forward
files that pass session checks but fail delivery later down the chain,
within the user mda

fix remote buffer overflow in unprivileged pony process

reworked offline enqueue to better protect against hardlink attacks