irqreturn_t ipmi_si_irq_handler(int irq, void *data)
{
	struct smi_info *smi_info = data;
	unsigned long   flags;

	if (smi_info->io.si_type == SI_BT)
		/* We need to clear the IRQ flag for the BT interface. */
		smi_info->io.outputb(&smi_info->io, IPMI_BT_INTMASK_REG,
				     IPMI_BT_INTMASK_CLEAR_IRQ_BIT
				     | IPMI_BT_INTMASK_ENABLE_IRQ_BIT);

	spin_lock_irqsave(&(smi_info->si_lock), flags);

	smi_inc_stat(smi_info, interrupts);

	debug_timestamp("Interrupt");

	smi_event_handler(smi_info, 0);
	spin_unlock_irqrestore(&(smi_info->si_lock), flags);
	return IRQ_HANDLED;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.