hold task_lock around checks in keyctl

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0291b3f..f1b59ae 100644 (file)
--- 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)