diff options
Diffstat (limited to 'drivers/char/tty_io.c')
| -rw-r--r-- | drivers/char/tty_io.c | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index eb881cfa53e0..2a1e95b0f282 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -2770,12 +2770,11 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) * actually has driver level meaning and triggers a VC resize. * * Locking: - * The console_sem is used to ensure we do not try and resize - * the console twice at once. - * FIXME: Two racing size sets may leave the console and kernel - * parameters disagreeing. Is this exploitable ? - * FIXME: Random values racing a window size get is wrong - * should lock here against that + * Called function use the console_sem is used to ensure we do + * not try and resize the console twice at once. + * The tty->termios_sem is used to ensure we don't double + * resize and get confused. Lock order - tty->termios.sem before + * console sem */ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, @@ -2785,17 +2784,17 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, if (copy_from_user(&tmp_ws, arg, sizeof(*arg))) return -EFAULT; + + down(&tty->termios_sem); if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg))) - return 0; + goto done; + #ifdef CONFIG_VT if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) { - int rc; - - acquire_console_sem(); - rc = vc_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row); - release_console_sem(); - if (rc) - return -ENXIO; + if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row)) { + up(&tty->termios_sem); + return -ENXIO; + } } #endif if (tty->pgrp > 0) @@ -2804,6 +2803,8 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, kill_pg(real_tty->pgrp, SIGWINCH, 1); tty->winsize = tmp_ws; real_tty->winsize = tmp_ws; +done: + up(&tty->termios_sem); return 0; } |