diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2013-03-06 17:38:19 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-19 03:13:59 +0400 |
| commit | 8c985d18b136c5d511445d15f0c6650003a8946b (patch) | |
| tree | 37bccfd3f1c965f793bc8f039360e460d38f5a44 /drivers | |
| parent | e91e52e42814b130c20d17bc1e2adf813c50db11 (diff) | |
| download | linux-8c985d18b136c5d511445d15f0c6650003a8946b.tar.xz | |
n_tty: Fix unsafe driver-side signals
An ldisc reference is insufficient guarantee the foreground process
group is not in the process of being signalled from a hangup.
1) Reads of tty->pgrp must be locked with ctrl_lock
2) The group pid must be referenced for the duration of signalling.
Because the driver-side is not process-context, a pid reference
must be acquired.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/n_tty.c | 34 |
1 files changed, 14 insertions, 20 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index e3a9321f7f89..61f1bc97ccd9 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1017,23 +1017,19 @@ static void eraser(unsigned char c, struct tty_struct *tty) * isig - handle the ISIG optio * @sig: signal * @tty: terminal - * @flush: force flush * - * Called when a signal is being sent due to terminal input. This - * may caus terminal flushing to take place according to the termios - * settings and character used. Called from the driver receive_buf - * path so serialized. + * Called when a signal is being sent due to terminal input. + * Called from the driver receive_buf path so serialized. * - * Locking: ctrl_lock, read_lock (both via flush buffer) + * Locking: ctrl_lock */ -static inline void isig(int sig, struct tty_struct *tty, int flush) +static inline void isig(int sig, struct tty_struct *tty) { - if (tty->pgrp) - kill_pgrp(tty->pgrp, sig, 1); - if (flush || !L_NOFLSH(tty)) { - n_tty_flush_buffer(tty); - tty_driver_flush_buffer(tty); + struct pid *tty_pgrp = tty_get_pgrp(tty); + if (tty_pgrp) { + kill_pgrp(tty_pgrp, sig, 1); + put_pid(tty_pgrp); } } @@ -1054,7 +1050,11 @@ static inline void n_tty_receive_break(struct tty_struct *tty) if (I_IGNBRK(tty)) return; if (I_BRKINT(tty)) { - isig(SIGINT, tty, 1); + isig(SIGINT, tty); + if (!L_NOFLSH(tty)) { + n_tty_flush_buffer(tty); + tty_driver_flush_buffer(tty); + } return; } if (I_PARMRK(tty)) { @@ -1221,11 +1221,6 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) signal = SIGTSTP; if (c == SUSP_CHAR(tty)) { send_signal: - /* - * Note that we do not use isig() here because we want - * the order to be: - * 1) flush, 2) echo, 3) signal - */ if (!L_NOFLSH(tty)) { n_tty_flush_buffer(tty); tty_driver_flush_buffer(tty); @@ -1236,8 +1231,7 @@ send_signal: echo_char(c, tty); process_echoes(tty); } - if (tty->pgrp) - kill_pgrp(tty->pgrp, signal, 1); + isig(signal, tty); return; } } |