int ipmi_si_port_setup(struct si_sm_io *io)
{
	unsigned int addr = io->addr_data;
	int          idx;

 	if (!addr)
 		return -ENODEV;
 
 	/*
 	 * Figure out the actual inb/inw/inl/etc routine to use based
 	 * upon the register size.
	 */
	switch (io->regsize) {
	case 1:
		io->inputb = port_inb;
		io->outputb = port_outb;
		break;
	case 2:
		io->inputb = port_inw;
		io->outputb = port_outw;
		break;
	case 4:
		io->inputb = port_inl;
		io->outputb = port_outl;
		break;
	default:
		dev_warn(io->dev, "Invalid register size: %d\n",
			 io->regsize);
		return -EINVAL;
	}

	/*
	 * Some BIOSes reserve disjoint I/O regions in their ACPI
	 * tables.  This causes problems when trying to register the
	 * entire I/O region.  Therefore we must register each I/O
	 * port separately.
	 */
	for (idx = 0; idx < io->io_size; idx++) {
		if (request_region(addr + idx * io->regspacing,
				   io->regsize, DEVICE_NAME) == NULL) {
			/* Undo allocations */
			while (idx--)
				release_region(addr + idx * io->regspacing,
					       io->regsize);
 			return -EIO;
 		}
 	}

	io->io_cleanup = port_cleanup;

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.