static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
			 int nr_wake, int nr_requeue, u32 *cmpval,
			 int requeue_pi)
{
	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
	int drop_count = 0, task_count = 0, ret;
	struct futex_pi_state *pi_state = NULL;
	struct futex_hash_bucket *hb1, *hb2;
	struct plist_head *head1;
	struct futex_q *this, *next;
	u32 curval2;

	if (requeue_pi) {
		/*
		 * requeue_pi requires a pi_state, try to allocate it now
		 * without any locks in case it fails.
		 */
		if (refill_pi_state_cache())
			return -ENOMEM;
		/*
		 * requeue_pi must wake as many tasks as it can, up to nr_wake
		 * + nr_requeue, since it acquires the rt_mutex prior to
		 * returning to userspace, so as to not leave the rt_mutex with
		 * waiters and no owner.  However, second and third wake-ups
		 * cannot be predicted as they involve race conditions with the
		 * first wake and a fault while looking up the pi_state.  Both
		 * pthread_cond_signal() and pthread_cond_broadcast() should
		 * use nr_wake=1.
		 */
		if (nr_wake != 1)
			return -EINVAL;
	}

retry:
	if (pi_state != NULL) {
		/*
		 * We will have to lookup the pi_state again, so free this one
		 * to keep the accounting correct.
		 */
		free_pi_state(pi_state);
		pi_state = NULL;
	}

	ret = get_futex_key(uaddr1, fshared, &key1);
	if (unlikely(ret != 0))
		goto out;
	ret = get_futex_key(uaddr2, fshared, &key2);
	if (unlikely(ret != 0))
		goto out_put_key1;

	hb1 = hash_futex(&key1);
	hb2 = hash_futex(&key2);

retry_private:
	double_lock_hb(hb1, hb2);

	if (likely(cmpval != NULL)) {
		u32 curval;

		ret = get_futex_value_locked(&curval, uaddr1);

		if (unlikely(ret)) {
			double_unlock_hb(hb1, hb2);

			ret = get_user(curval, uaddr1);
			if (ret)
				goto out_put_keys;

			if (!fshared)
				goto retry_private;

			put_futex_key(fshared, &key2);
			put_futex_key(fshared, &key1);
			goto retry;
		}
		if (curval != *cmpval) {
			ret = -EAGAIN;
			goto out_unlock;
		}
	}

	if (requeue_pi && (task_count - nr_wake < nr_requeue)) {
		/*
		 * Attempt to acquire uaddr2 and wake the top waiter. If we
		 * intend to requeue waiters, force setting the FUTEX_WAITERS
		 * bit.  We force this here where we are able to easily handle
		 * faults rather in the requeue loop below.
		 */
		ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1,
						 &key2, &pi_state, nr_requeue);

		/*
		 * At this point the top_waiter has either taken uaddr2 or is
		 * waiting on it.  If the former, then the pi_state will not
		 * exist yet, look it up one more time to ensure we have a
		 * reference to it.
		 */
		if (ret == 1) {
			WARN_ON(pi_state);
			drop_count++;
			task_count++;
			ret = get_futex_value_locked(&curval2, uaddr2);
			if (!ret)
				ret = lookup_pi_state(curval2, hb2, &key2,
						      &pi_state);
		}

		switch (ret) {
		case 0:
			break;
		case -EFAULT:
			double_unlock_hb(hb1, hb2);
			put_futex_key(fshared, &key2);
			put_futex_key(fshared, &key1);
			ret = fault_in_user_writeable(uaddr2);
			if (!ret)
				goto retry;
			goto out;
		case -EAGAIN:
			/* The owner was exiting, try again. */
			double_unlock_hb(hb1, hb2);
			put_futex_key(fshared, &key2);
			put_futex_key(fshared, &key1);
			cond_resched();
			goto retry;
		default:
			goto out_unlock;
		}
	}

	head1 = &hb1->chain;
	plist_for_each_entry_safe(this, next, head1, list) {
		if (task_count - nr_wake >= nr_requeue)
			break;

		if (!match_futex(&this->key, &key1))
			continue;

		/*
		 * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always
		 * be paired with each other and no other futex ops.
		 */
		if ((requeue_pi && !this->rt_waiter) ||
		    (!requeue_pi && this->rt_waiter)) {
			ret = -EINVAL;
			break;
		}

		/*
		 * Wake nr_wake waiters.  For requeue_pi, if we acquired the
		 * lock, we already woke the top_waiter.  If not, it will be
		 * woken by futex_unlock_pi().
		 */
		if (++task_count <= nr_wake && !requeue_pi) {
			wake_futex(this);
			continue;
		}

		/* Ensure we requeue to the expected futex for requeue_pi. */
		if (requeue_pi && !match_futex(this->requeue_pi_key, &key2)) {
			ret = -EINVAL;
			break;
		}

		/*
		 * Requeue nr_requeue waiters and possibly one more in the case
		 * of requeue_pi if we couldn't acquire the lock atomically.
		 */
		if (requeue_pi) {
			/* Prepare the waiter to take the rt_mutex. */
			atomic_inc(&pi_state->refcount);
			this->pi_state = pi_state;
			ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
							this->rt_waiter,
							this->task, 1);
			if (ret == 1) {
				/* We got the lock. */
				requeue_pi_wake_futex(this, &key2, hb2);
				drop_count++;
				continue;
			} else if (ret) {
				/* -EDEADLK */
				this->pi_state = NULL;
				free_pi_state(pi_state);
				goto out_unlock;
			}
		}
		requeue_futex(this, hb1, hb2, &key2);
		drop_count++;
	}

out_unlock:
	double_unlock_hb(hb1, hb2);

	/*
	 * drop_futex_key_refs() must be called outside the spinlocks. During
	 * the requeue we moved futex_q's from the hash bucket at key1 to the
	 * one at key2 and updated their key pointer.  We no longer need to
	 * hold the references to key1.
	 */
	while (--drop_count >= 0)
		drop_futex_key_refs(&key1);

out_put_keys:
	put_futex_key(fshared, &key2);
out_put_key1:
	put_futex_key(fshared, &key1);
out:
	if (pi_state != NULL)
		free_pi_state(pi_state);
	return ret ? ret : task_count;
}

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.