| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.12 118/212] tty: Reset hupped state on open | Date | Mon, 2 Dec 2013 11:15:09 -0800 |
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3.12-stable review patch. If anyone has any objections, please let me know.
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From: Peter Hurley <peter@hurleysoftware.com>
commit d4855e1fc03c2bb32dd64badf51cec5a2a26ab2a upstream.
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> Tested-by: Heorhi Valakhanovich <valahanovich@tut.by> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/tty/tty_io.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -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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