futex: Use pi_state_update_owner() in put_pi_state()

stable inclusion
from linux-4.19.172
commit 9d5dbf57d66f410d35da822a115dfd57531950dc
CVE: CVE-2021-3347

--------------------------------

commit 6ccc84f9 upstream

No point in open coding it. This way it gains the extra sanity checks.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

kernel/futex.c

@@ -883,15 +883,9 @@ static void put_pi_state(struct futex_pi_state *pi_state)
 	 * and has cleaned up the pi_state already
 	 */
 	if (pi_state->owner) {
-		struct task_struct *owner;
 
 		raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
-		owner = pi_state->owner;
-		if (owner) {
-			raw_spin_lock(&owner->pi_lock);
-			list_del_init(&pi_state->list);
-			raw_spin_unlock(&owner->pi_lock);
-		}
+		pi_state_update_owner(pi_state, NULL);
 		rt_mutex_proxy_unlock(&pi_state->pi_mutex);
 		raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
 	}