diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0291b3f9397c..f1b59ae39d7e 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1486,6 +1486,7 @@ long keyctl_session_to_parent(void)
 	oldwork = NULL;
 	parent = me->real_parent;
 
+	task_lock(parent);
 	/* the parent mustn't be init and mustn't be a kernel thread */
 	if (parent->pid <= 1 || !parent->mm)
 		goto unlock;
@@ -1529,6 +1530,7 @@ long keyctl_session_to_parent(void)
 	if (!ret)
 		newwork = NULL;
 unlock:
+	task_unlock(parent);
 	write_unlock_irq(&tasklist_lock);
 	rcu_read_unlock();
 	if (oldwork)