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

From	Peter Hurley <peter@hurleysoftware.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 06/19] tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)
Date	2016-01-10 06:30 +0100
Message-ID	<qPgJJ-8fM-3@gated-at.bofh.it> (permalink)
References	<qzyUh-8cQ-9@gated-at.bofh.it> <qPg6Z-7Hn-3@gated-at.bofh.it> <qPg70-7Hn-17@gated-at.bofh.it>
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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

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[PATCH v2 06/19] tty: Fix unsafe ldisc reference via ioctl(TIOCGETD) Peter Hurley <peter@hurleysoftware.com> - 2016-01-10 05:50 +0100
  Re: [PATCH v2 06/19] tty: Fix unsafe ldisc reference via  ioctl(TIOCGETD) Peter Hurley <peter@hurleysoftware.com> - 2016-01-10 06:30 +0100

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