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>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 57fc6ee..6bdfb98 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -388,33 +388,40 @@
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;
}