Re: [PATCH v2 06/19] tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)

[Peter Hurley]

On 01/09/2016 08:40 PM, Peter Hurley wrote:
> ioctl(TIOCGETD) retrieves the line discipline id directly from the
> ldisc because the line discipline id (c_line) in termios is untrustworthy;
> userspace may have set termios via ioctl(TCSETS*) without actually
> changing the line discipline via ioctl(TIOCSETD).
> 
> However, directly accessing the current ldisc via tty->ldisc is
> unsafe; the ldisc ptr dereferenced may be stale if the line discipline
> is changing via ioctl(TIOCSETD) or hangup.
> 
> Wait for the line discipline reference (just like read() or write())
> to retrieve the "current" line discipline id.

Hi Greg,

I forgot to re-mark this patch for stable.

Regards,
Peter Hurley