Commit 6719693c authored by Patrick Donnelly's avatar Patrick Donnelly Committed by Greg Kroah-Hartman
Browse files

tty: add missing rcu_read_lock for task_pgrp 



task_pgrp requires an rcu or tasklist lock to be obtained if the returned pid
is to be dereferenced, which kill_pgrp does. Obtain an RCU lock for the
duration of use.

Signed-off-by: default avatarPatrick Donnelly <batrick@batbytes.com>
Reviewed-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent da891641

drivers/tty/n_tty.c

+12 −3
Original line number Diff line number Diff line
@@ -2137,6 +2137,8 @@ extern ssize_t redirected_tty_write(struct file *, const char __user *, 


static int job_control(struct tty_struct *tty, struct file *file)

{

	struct pid *pgrp;



	/* Job control check -- must be done at start and after

	   every sleep (POSIX.1 7.1.1.4). */

	/* NOTE: not yet done after every sleep pending a thorough
@@ -2146,18 +2148,25 @@ static int job_control(struct tty_struct *tty, struct file *file) 
	    current->signal->tty != tty)

		return 0;



	rcu_read_lock();

	pgrp = task_pgrp(current);



	spin_lock_irq(&tty->ctrl_lock);

	if (!tty->pgrp)

		printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");

	else if (task_pgrp(current) != tty->pgrp) {

	else if (pgrp != tty->pgrp) {

		spin_unlock_irq(&tty->ctrl_lock);

		if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())

		if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) {

			rcu_read_unlock();

			return -EIO;

		kill_pgrp(task_pgrp(current), SIGTTIN, 1);

		}

		kill_pgrp(pgrp, SIGTTIN, 1);

		rcu_read_unlock();

		set_thread_flag(TIF_SIGPENDING);

		return -ERESTARTSYS;

	}

	spin_unlock_irq(&tty->ctrl_lock);

	rcu_read_unlock();

	return 0;

}

drivers/tty/tty_io.c

+12 −5
Original line number Diff line number Diff line
@@ -388,33 +388,40 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver); 
int tty_check_change(struct tty_struct *tty)

{

	unsigned long flags;

	struct pid *pgrp;

	int ret = 0;



	if (current->signal->tty != tty)

		return 0;



	rcu_read_lock();

	pgrp = task_pgrp(current);



	spin_lock_irqsave(&tty->ctrl_lock, flags);



	if (!tty->pgrp) {

		printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");

		goto out_unlock;

	}

	if (task_pgrp(current) == tty->pgrp)

	if (pgrp == tty->pgrp)

		goto out_unlock;

	spin_unlock_irqrestore(&tty->ctrl_lock, flags);



	if (is_ignored(SIGTTOU))

		goto out;

		goto out_rcuunlock;

	if (is_current_pgrp_orphaned()) {

		ret = -EIO;

		goto out;

		goto out_rcuunlock;

	}

	kill_pgrp(task_pgrp(current), SIGTTOU, 1);

	kill_pgrp(pgrp, SIGTTOU, 1);

	rcu_read_unlock();

	set_thread_flag(TIF_SIGPENDING);

	ret = -ERESTARTSYS;

out:

	return ret;

out_unlock:

	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

out_rcuunlock:

	rcu_read_unlock();

	return ret;

}

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