2.3.11 (or earlier?) introduced 'plugin' option, and one of hooks
plugins can define is 'pap_auth_hook' that can return a wordlist of
additional options for this particular user.  This is relly very
good and useful feature, as there is at least some demand on having
separate options for each (group of) user.  But if that hook sets up
option list, pppd will loop forever eating 100% cpu and ignoring signals
(except -9), and sitting "on line" with tty opened, preventing this line
to be dialed in.  I quickly made my dial-in server unusable when all
16 modem lines was locked by looped pppd, thus preventing any dial-in...
Ok, fix is trivial, it is in `options_from_list()' routine -- it checks
the first option again and again wihout jumping to next one...
As such, this routine was _never_ checked/executed by author/testers/users!

I'll not forward this report/fix to pppd author, as it is useless.
He just ignores any letters sent to him (as I can guess) -- I sent many,
many bugreports to him without any responce...

BTW, does anybody knows where is a current home for pppd?
I saw 2.4.0 pre/beta somewhere, but it is not in usual location...

P.S.  I see that RedHat also isn't very "responsible" for ppp package... :(