Re: autoloading compat43 on tty ioctls

[christos%astron.com@localhost (Christos Zoulas)]

In article <20201010133342.GA13631%homeworld.netbsd.org@localhost>,
nia  <nia%NetBSD.org@localhost> wrote:
>syzkaller found a bug in tty_43.c which i noticed could lock up my
>system after i wrote a reproducer for it.
>
>i was curious why 43bsd compat is enabled by default on amd64 then
>noticed it gets loaded by tty if it detects an unrecognized ioctl
>
>https://github.com/NetBSD/src/blob/trunk/sys/kern/tty.c#L1420
>
>this seems to be a strange choice, especially on archs that never ran
>43bsd binaries. were applications relying on these ioctls more recently?
>
>i'm not familiar with the history of this code, but maybe someone here is

Aside for the TIOCGSID bug which I am about to fix (it is in tty_43.c
and is used in libc tcgetsid(), all the compat tty ioctls are defined
in /usr/src/sys/sys/ioctl_compat.h... We can empty that file and try
to build the tree :-), but I am guessing things will break. Also a lot
of pkgsrc will break too. It is not 4.3 applications that break it is
applications that still use the 4.3 terminal api's.

christos