diff options
| -rw-r--r-- | drivers/tty/tty_io.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index b645519300c2..114854c5554b 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -502,8 +502,15 @@ void proc_clear_tty(struct task_struct *p) tty_kref_put(tty); } -/* Called under the sighand lock */ - +/** + * proc_set_tty - set the controlling terminal + * + * Only callable by the session leader and only if it does not already have + * a controlling terminal. + * + * Caller must hold: a readlock on tasklist_lock + * sighand lock + */ static void __proc_set_tty(struct tty_struct *tty) { unsigned long flags; @@ -2150,6 +2157,7 @@ retry_open: mutex_lock(&tty_mutex); tty_lock(tty); + read_lock(&tasklist_lock); spin_lock_irq(¤t->sighand->siglock); if (!noctty && current->signal->leader && @@ -2157,6 +2165,7 @@ retry_open: tty->session == NULL) __proc_set_tty(tty); spin_unlock_irq(¤t->sighand->siglock); + read_unlock(&tasklist_lock); tty_unlock(tty); mutex_unlock(&tty_mutex); return 0; @@ -2447,10 +2456,13 @@ static int fionbio(struct file *file, int __user *p) static int tiocsctty(struct tty_struct *tty, int arg) { int ret = 0; - if (current->signal->leader && (task_session(current) == tty->session)) - return ret; mutex_lock(&tty_mutex); + read_lock(&tasklist_lock); + + if (current->signal->leader && (task_session(current) == tty->session)) + goto unlock; + /* * The process must be a session leader and * not have a controlling tty already. @@ -2469,9 +2481,7 @@ static int tiocsctty(struct tty_struct *tty, int arg) /* * Steal it away */ - read_lock(&tasklist_lock); session_clear_tty(tty->session); - read_unlock(&tasklist_lock); } else { ret = -EPERM; goto unlock; @@ -2479,6 +2489,7 @@ static int tiocsctty(struct tty_struct *tty, int arg) } proc_set_tty(tty); unlock: + read_unlock(&tasklist_lock); mutex_unlock(&tty_mutex); return ret; } |