--- security/keys/keyctl.c

+++ security/keys/keyctl.c

@@ -1259,6 +1259,7 @@ long keyctl_session_to_parent(void)

keyring_r = NULL;

me = current;

+ rcu_read_lock();

write_lock_irq(&tasklist_lock);

parent = me->real_parent;

@@ -1291,7 +1292,8 @@ long keyctl_session_to_parent(void)

goto not_permitted;

/* the keyrings must have the same UID */

- if (pcred ->tgcred->session_keyring->uid != mycred->euid ||

+ if ((pcred->tgcred->session_keyring &&

+ pcred->tgcred->session_keyring->uid != mycred->euid) ||

mycred->tgcred->session_keyring->uid != mycred->euid)

goto not_permitted;

@@ -1313,6 +1315,7 @@ long keyctl_session_to_parent(void)

set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);

write_unlock_irq(&tasklist_lock);

+ rcu_read_unlock();

if (oldcred)

put_cred(oldcred);

return 0;

@@ -1321,6 +1324,7 @@ already_same:

ret = 0;

not_permitted:

write_unlock_irq(&tasklist_lock);

+ rcu_read_unlock();

put_cred(cred);

return ret;