Commit d4855e1f authored Nov 19, 2013 by Peter Hurley Committed by Greg Kroah-Hartman Nov 25, 2013

tty: Reset hupped state on open



A common security idiom is to hangup the current tty (via vhangup())
after forking but before execing a root shell. This hangs up any
existing opens which other processes may have and ensures subsequent
opens have the necessary permissions to open the root shell tty/pty.

Reset the TTY_HUPPED state after the driver has successfully
returned the opened tty (perform the reset while the tty is locked
to avoid racing with concurrent hangups).

Reported-by: Heorhi Valakhanovich <valahanovich@tut.by>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Cc: stable <stable@vger.kernel.org> # 3.12
Tested-by: Heorhi Valakhanovich <valahanovich@tut.by>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3dcf344b

drivers/tty/tty_io.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2086,6 +2086,7 @@ retry_open:
		filp->f_op = &tty_fops;
		goto retry_open;
		}
		clear_bit(TTY_HUPPED, &tty->flags);
		tty_unlock(tty);

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