static int ion_debug_client_show(struct seq_file *s, void *unused)
{
	struct ion_client *client = s->private;
	struct rb_node *n;
	size_t sizes[ION_NUM_HEAP_IDS] = {0};
	const char *names[ION_NUM_HEAP_IDS] = {NULL};
	int i;

	mutex_lock(&debugfs_mutex);
	if (!is_client_alive(client)) {
		seq_printf(s, "ion_client 0x%p dead, can't dump its buffers\n",
			   client);
		mutex_unlock(&debugfs_mutex);
		return 0;
	}

	mutex_lock(&client->lock);
	for (n = rb_first(&client->handles); n; n = rb_next(n)) {
		struct ion_handle *handle = rb_entry(n, struct ion_handle,
						     node);
		unsigned int id = handle->buffer->heap->id;

		if (!names[id])
			names[id] = handle->buffer->heap->name;
		sizes[id] += handle->buffer->size;
	}
	mutex_unlock(&client->lock);
	mutex_unlock(&debugfs_mutex);

	seq_printf(s, "%16.16s: %16.16s\n", "heap_name", "size_in_bytes");
	for (i = 0; i < ION_NUM_HEAP_IDS; i++) {
		if (!names[i])
			continue;
		seq_printf(s, "%16.16s: %16zu\n", names[i], sizes[i]);
	}
	return 0;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.