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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: Patrick Donnelly <batrick@batbytes.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Patrick Donnelly 2015-07-12 18:51:52 -04:00 committed by Greg Kroah-Hartman
parent da891641b6
commit 6719693ca2
2 changed files with 24 additions and 8 deletions
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15
drivers/tty/n_tty.c
View File

@ -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;
}

17
drivers/tty/tty_io.c
View File

@ -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;
}