Merging upstream version 4.19.304.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/drivers/tty/tty_jobctrl.c b/drivers/tty/tty_jobctrl.c
index ffcab80ba..73fdd55c6 100644
--- a/drivers/tty/tty_jobctrl.c
+++ b/drivers/tty/tty_jobctrl.c
@@ -290,12 +290,7 @@ void disassociate_ctty(int on_exit)
 		return;
 	}
 
-	spin_lock_irq(&current->sighand->siglock);
-	put_pid(current->signal->tty_old_pgrp);
-	current->signal->tty_old_pgrp = NULL;
-	tty = tty_kref_get(current->signal->tty);
-	spin_unlock_irq(&current->sighand->siglock);
-
+	tty = get_current_tty();
 	if (tty) {
 		unsigned long flags;
 
@@ -310,6 +305,16 @@ void disassociate_ctty(int on_exit)
 		tty_kref_put(tty);
 	}
 
+	/* If tty->ctrl.pgrp is not NULL, it may be assigned to
+	 * current->signal->tty_old_pgrp in a race condition, and
+	 * cause pid memleak. Release current->signal->tty_old_pgrp
+	 * after tty->ctrl.pgrp set to NULL.
+	 */
+	spin_lock_irq(&current->sighand->siglock);
+	put_pid(current->signal->tty_old_pgrp);
+	current->signal->tty_old_pgrp = NULL;
+	spin_unlock_irq(&current->sighand->siglock);
+
 	/* Now clear signal->tty under the lock */
 	read_lock(&tasklist_lock);
 	session_clear_tty(task_session(current));