int ipmi_si_add_smi(struct si_sm_io *io)
{
	int rv = 0;
	struct smi_info *new_smi, *dup;

	if (!io->io_setup) {
		if (io->addr_type == IPMI_IO_ADDR_SPACE) {
			io->io_setup = ipmi_si_port_setup;
		} else if (io->addr_type == IPMI_MEM_ADDR_SPACE) {
			io->io_setup = ipmi_si_mem_setup;
		} else {
			return -EINVAL;
		}
	}

	new_smi = kzalloc(sizeof(*new_smi), GFP_KERNEL);
	if (!new_smi)
		return -ENOMEM;
	spin_lock_init(&new_smi->si_lock);

	new_smi->io = *io;

	mutex_lock(&smi_infos_lock);
	dup = find_dup_si(new_smi);
	if (dup) {
		if (new_smi->io.addr_source == SI_ACPI &&
		    dup->io.addr_source == SI_SMBIOS) {
			/* We prefer ACPI over SMBIOS. */
			dev_info(dup->io.dev,
				 "Removing SMBIOS-specified %s state machine in favor of ACPI\n",
				 si_to_str[new_smi->io.si_type]);
			cleanup_one_si(dup);
		} else {
			dev_info(new_smi->io.dev,
				 "%s-specified %s state machine: duplicate\n",
				 ipmi_addr_src_to_str(new_smi->io.addr_source),
				 si_to_str[new_smi->io.si_type]);
			rv = -EBUSY;
			kfree(new_smi);
			goto out_err;
		}
	}

	pr_info("Adding %s-specified %s state machine\n",
		ipmi_addr_src_to_str(new_smi->io.addr_source),
		si_to_str[new_smi->io.si_type]);

	list_add_tail(&new_smi->link, &smi_infos);

	if (initialized)
		rv = try_smi_init(new_smi);
out_err:
	mutex_unlock(&smi_infos_lock);
	return rv;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.