From d4855e1fc03c2bb32dd64badf51cec5a2a26ab2a Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Tue, 19 Nov 2013 08:46:27 -0500 Subject: [PATCH] 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 Signed-off-by: Peter Hurley Cc: stable # 3.12 Tested-by: Heorhi Valakhanovich Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_io.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 3a1a01af9a80..c74a00ad7add 100644 --- 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);