struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
{
	struct sighand_struct *sighand;

	for (;;) {
		/*
		 * Disable interrupts early to avoid deadlocks.
		 * See rcu_read_unlock() comment header for details.
		 */
		local_irq_save(*flags);
		rcu_read_lock();
		sighand = rcu_dereference(tsk->sighand);
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
			break;
		}
		/*
		 * This sighand can be already freed and even reused, but
		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
		 * initializes ->siglock: this slab can't go away, it has
		 * the same object type, ->siglock can't be reinitialized.
		 *
		 * We need to ensure that tsk->sighand is still the same
		 * after we take the lock, we can race with de_thread() or
		 * __exit_signal(). In the latter case the next iteration
		 * must see ->sighand == NULL.
		 */
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
			break;
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
	}

	return sighand;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.